diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1377554
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.swp
diff --git a/go.mod b/go.mod
index a68b5cd..8b8f830 100644
--- a/go.mod
+++ b/go.mod
@@ -5,5 +5,6 @@ go 1.14
 require (
 	git.trj.tw/golang/utils v0.0.0-20190225142552-b019626f0349
 	github.com/BurntSushi/toml v0.3.1
+	github.com/otakukaze/envconfig v1.0.4
 	gopkg.in/yaml.v2 v2.3.0
 )
diff --git a/go.sum b/go.sum
index a50e755..313e2e2 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,8 @@ git.trj.tw/golang/utils v0.0.0-20190225142552-b019626f0349 h1:V6ifeiJ3ExnjaUylTO
 git.trj.tw/golang/utils v0.0.0-20190225142552-b019626f0349/go.mod h1:yE+qbsUsijCTdwsaQRkPT1CXYk7ftMzXsCaaYx/0QI0=
 github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/otakukaze/envconfig v1.0.4 h1:/rZ8xq1vFpgWzqsqUkk61doDGNv9pIXqrog/mCvSx8Y=
+github.com/otakukaze/envconfig v1.0.4/go.mod h1:v2dNv5NX1Lakw3FTAkbxYURyaiOy68M8QpMTZz+ogfs=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
diff --git a/loader.go b/loader.go
index 9deffd0..7a6639a 100644
--- a/loader.go
+++ b/loader.go
@@ -9,6 +9,7 @@ import (
 
 	"git.trj.tw/golang/utils"
 	"github.com/BurntSushi/toml"
+	"github.com/otakukaze/envconfig"
 	"gopkg.in/yaml.v2"
 )
 
@@ -27,6 +28,7 @@ type ConfigFile struct {
 
 type LoadOptions struct {
 	ConfigFile *ConfigFile
+	FromEnv    bool
 }
 
 func Load(i interface{}, opts *LoadOptions) error {
@@ -50,48 +52,51 @@ func Load(i interface{}, opts *LoadOptions) error {
 		return nil
 	}
 
-	// no config file
-	if opts.ConfigFile == nil {
-		return nil
-	}
+	// load config file
+	if opts.ConfigFile != nil {
+		if opts.ConfigFile.Path == "" {
+			return errors.New("config file path empty")
+		}
 
-	if opts.ConfigFile.Path == "" {
-		return errors.New("config file path empty")
-	}
+		// resolve file path
+		opts.ConfigFile.Path = utils.ParsePath(opts.ConfigFile.Path)
+		// check file exists
+		if !utils.CheckExists(opts.ConfigFile.Path, false) {
+			return errors.New("config file not found")
+		}
 
-	// resolve file path
-	opts.ConfigFile.Path = utils.ParsePath(opts.ConfigFile.Path)
-	// check file exists
-	if !utils.CheckExists(opts.ConfigFile.Path, false) {
-		return errors.New("config file not found")
-	}
-
-	filebyte, err := ioutil.ReadFile(opts.ConfigFile.Path)
-	if err != nil {
-		return err
-	}
-
-	switch opts.ConfigFile.Type {
-	case ConfigFileTypeJSON:
-		err := json.Unmarshal(filebyte, i)
+		filebyte, err := ioutil.ReadFile(opts.ConfigFile.Path)
 		if err != nil {
 			return err
 		}
-		break
-	case ConfigFileTypeTOML:
-		err := toml.Unmarshal(filebyte, i)
-		if err != nil {
-			return err
+
+		switch opts.ConfigFile.Type {
+		case ConfigFileTypeJSON:
+			err := json.Unmarshal(filebyte, i)
+			if err != nil {
+				return err
+			}
+			break
+		case ConfigFileTypeTOML:
+			err := toml.Unmarshal(filebyte, i)
+			if err != nil {
+				return err
+			}
+			break
+		case ConfigFileTypeYAML:
+			err := yaml.Unmarshal(filebyte, i)
+			if err != nil {
+				return err
+			}
+			break
+		default:
+			return errors.New("file type not impl")
 		}
-		break
-	case ConfigFileTypeYAML:
-		err := yaml.Unmarshal(filebyte, i)
-		if err != nil {
-			return err
-		}
-		break
-	default:
-		return errors.New("file type not impl")
+	}
+
+	// load config from env
+	if opts.FromEnv {
+		envconfig.Parse(i)
 	}
 
 	return nil
diff --git a/loader_test.go b/loader_test.go
index 9430508..35da841 100644
--- a/loader_test.go
+++ b/loader_test.go
@@ -1,6 +1,7 @@
 package confloader
 
 import (
+	"os"
 	"reflect"
 	"testing"
 )
@@ -13,8 +14,8 @@ func TestLoad(t *testing.T) {
 		Key string `json:"key" yaml:"key" toml:"key"`
 	}
 	type Config struct {
-		StrKey   string   `json:"strKey" yaml:"strKey" toml:"strKey" default:"def value"`
-		IntKey   int      `json:"intKey" yaml:"intKey" toml:"intKey"`
+		StrKey   string   `json:"strKey" yaml:"strKey" toml:"strKey" default:"def value" env:"TEST_STR"`
+		IntKey   int      `json:"intKey" yaml:"intKey" toml:"intKey" env:"TEST_INT"`
 		BoolKey  bool     `json:"boolKey" yaml:"boolKey" toml:"boolKey"`
 		FloatKey float64  `json:"floatKey" yaml:"floatKey" toml:"floatKey"`
 		StrArr   []string `json:"strArr" yaml:"strArr" toml:"strArr" default:"arrval" length:"1"`
@@ -23,6 +24,9 @@ func TestLoad(t *testing.T) {
 		ArrObj   []ArrObj `json:"arrObj" yaml:"arrObj" toml:"arrObj"`
 	}
 
+	os.Setenv("TEST_STR", "string value2")
+	os.Setenv("TEST_INT", "2000")
+
 	expected := Config{
 		StrKey:   "string value",
 		IntKey:   1000,
@@ -35,8 +39,20 @@ func TestLoad(t *testing.T) {
 		},
 		ArrObj: []ArrObj{{Key: "val"}},
 	}
+	expectedWithEnv := Config{
+		StrKey:   "string value2",
+		IntKey:   2000,
+		BoolKey:  true,
+		FloatKey: 1.2345,
+		StrArr:   []string{"arr1"},
+		StrArr2:  []string{"arrval2", "arrval2"},
+		ObjKey: ObjKey{
+			Name: "name",
+		},
+		ArrObj: []ArrObj{{Key: "val"}},
+	}
 
-	src := Config{}
+	// src := Config{}
 
 	type args struct {
 		i    interface{}
@@ -51,7 +67,6 @@ func TestLoad(t *testing.T) {
 		{
 			name: "test load json file with default",
 			args: args{
-				i: &src,
 				opts: &LoadOptions{
 					ConfigFile: &ConfigFile{
 						Type: ConfigFileTypeJSON,
@@ -64,7 +79,6 @@ func TestLoad(t *testing.T) {
 		{
 			name: "test load yaml file with default",
 			args: args{
-				i: &src,
 				opts: &LoadOptions{
 					ConfigFile: &ConfigFile{
 						Type: ConfigFileTypeYAML,
@@ -77,7 +91,6 @@ func TestLoad(t *testing.T) {
 		{
 			name: "test load toml file with default",
 			args: args{
-				i: &src,
 				opts: &LoadOptions{
 					ConfigFile: &ConfigFile{
 						Type: ConfigFileTypeTOML,
@@ -87,14 +100,35 @@ func TestLoad(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "test load json file with default and env",
+			args: args{
+				opts: &LoadOptions{
+					ConfigFile: &ConfigFile{
+						Type: ConfigFileTypeJSON,
+						Path: "./test/config.json",
+					},
+					FromEnv: true,
+				},
+			},
+			wantErr: false,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			src := Config{}
+			tt.args.i = &src
 			if err := Load(tt.args.i, tt.args.opts); (err != nil) != tt.wantErr {
 				t.Errorf("Load() error = %v, wantErr %v", err, tt.wantErr)
 			}
-			if !reflect.DeepEqual(src, expected) {
-				t.Errorf("Load and expected not match")
+			if tt.args.opts != nil && tt.args.opts.FromEnv {
+				if !reflect.DeepEqual(src, expectedWithEnv) {
+					t.Errorf("Load and expected not match")
+				}
+			} else {
+				if !reflect.DeepEqual(src, expected) {
+					t.Errorf("Load and expected not match")
+				}
 			}
 		})
 	}