diff --git a/README.md b/README.md
index 2d640d74c..48d0537db 100644
--- a/README.md
+++ b/README.md
@@ -109,10 +109,10 @@ Proxy:
 
 Proxy Group:
 # url-test select which proxy will be used by benchmarking speed to a URL.
-- { name: "auto", type: url-test, proxies: ["ss1", "ss2", "vmess1"], url: http://www.gstatic.com/generate_204, delay: 300 }
+- { name: "auto", type: url-test, proxies: ["ss1", "ss2", "vmess1"], url: http://www.gstatic.com/generate_204, interval: 300 }
 
 # fallback select an available policy by priority. The availability is tested by accessing an URL, just like an auto url-test group.
-- { name: "fallback-auto", type: fallback, proxies: ["ss1", "ss2", "vmess1"], url: http://www.gstatic.com/generate_204, delay: 300 }
+- { name: "fallback-auto", type: fallback, proxies: ["ss1", "ss2", "vmess1"], url: http://www.gstatic.com/generate_204, interval: 300 }
 
 # select is used for selecting proxy or proxy group
 # you can use RESTful API to switch proxy, is recommended for use in GUI.
diff --git a/adapters/outbound/fallback.go b/adapters/outbound/fallback.go
index 7057d0238..e858d0ab0 100644
--- a/adapters/outbound/fallback.go
+++ b/adapters/outbound/fallback.go
@@ -14,18 +14,18 @@ type proxy struct {
 }
 
 type Fallback struct {
-	name    string
-	proxies []*proxy
-	rawURL  string
-	delay   time.Duration
-	done    chan struct{}
+	name     string
+	proxies  []*proxy
+	rawURL   string
+	interval time.Duration
+	done     chan struct{}
 }
 
 type FallbackOption struct {
-	Name    string   `proxy:"name"`
-	Proxies []string `proxy:"proxies"`
-	URL     string   `proxy:"url"`
-	Delay   int      `proxy:"delay"`
+	Name     string   `proxy:"name"`
+	Proxies  []string `proxy:"proxies"`
+	URL      string   `proxy:"url"`
+	Interval int      `proxy:"interval"`
 }
 
 func (f *Fallback) Name() string {
@@ -68,7 +68,7 @@ func (f *Fallback) Close() {
 }
 
 func (f *Fallback) loop() {
-	tick := time.NewTicker(f.delay)
+	tick := time.NewTicker(f.interval)
 	go f.validTest()
 Loop:
 	for {
@@ -115,7 +115,7 @@ func NewFallback(option FallbackOption, proxies []C.Proxy) (*Fallback, error) {
 		return nil, errors.New("The number of proxies cannot be 0")
 	}
 
-	delay := time.Duration(option.Delay) * time.Second
+	interval := time.Duration(option.Interval) * time.Second
 	warpperProxies := make([]*proxy, len(proxies))
 	for idx := range proxies {
 		warpperProxies[idx] = &proxy{
@@ -125,11 +125,11 @@ func NewFallback(option FallbackOption, proxies []C.Proxy) (*Fallback, error) {
 	}
 
 	Fallback := &Fallback{
-		name:    option.Name,
-		proxies: warpperProxies,
-		rawURL:  option.URL,
-		delay:   delay,
-		done:    make(chan struct{}),
+		name:     option.Name,
+		proxies:  warpperProxies,
+		rawURL:   option.URL,
+		interval: interval,
+		done:     make(chan struct{}),
 	}
 	go Fallback.loop()
 	return Fallback, nil
diff --git a/adapters/outbound/urltest.go b/adapters/outbound/urltest.go
index c536e612f..df2be060d 100644
--- a/adapters/outbound/urltest.go
+++ b/adapters/outbound/urltest.go
@@ -9,19 +9,19 @@ import (
 )
 
 type URLTest struct {
-	name    string
-	proxies []C.Proxy
-	rawURL  string
-	fast    C.Proxy
-	delay   time.Duration
-	done    chan struct{}
+	name     string
+	proxies  []C.Proxy
+	rawURL   string
+	fast     C.Proxy
+	interval time.Duration
+	done     chan struct{}
 }
 
 type URLTestOption struct {
-	Name    string   `proxy:"name"`
-	Proxies []string `proxy:"proxies"`
-	URL     string   `proxy:"url"`
-	Delay   int      `proxy:"delay"`
+	Name     string   `proxy:"name"`
+	Proxies  []string `proxy:"proxies"`
+	URL      string   `proxy:"url"`
+	Interval int      `proxy:"interval"`
 }
 
 func (u *URLTest) Name() string {
@@ -45,7 +45,7 @@ func (u *URLTest) Close() {
 }
 
 func (u *URLTest) loop() {
-	tick := time.NewTicker(u.delay)
+	tick := time.NewTicker(u.interval)
 	go u.speedTest()
 Loop:
 	for {
@@ -63,7 +63,7 @@ func (u *URLTest) speedTest() {
 	wg.Add(len(u.proxies))
 	c := make(chan interface{})
 	fast := selectFast(c)
-	timer := time.NewTimer(u.delay)
+	timer := time.NewTimer(u.interval)
 
 	for _, p := range u.proxies {
 		go func(p C.Proxy) {
@@ -100,14 +100,14 @@ func NewURLTest(option URLTestOption, proxies []C.Proxy) (*URLTest, error) {
 		return nil, errors.New("The number of proxies cannot be 0")
 	}
 
-	delay := time.Duration(option.Delay) * time.Second
+	interval := time.Duration(option.Interval) * time.Second
 	urlTest := &URLTest{
-		name:    option.Name,
-		proxies: proxies[:],
-		rawURL:  option.URL,
-		fast:    proxies[0],
-		delay:   delay,
-		done:    make(chan struct{}),
+		name:     option.Name,
+		proxies:  proxies[:],
+		rawURL:   option.URL,
+		fast:     proxies[0],
+		interval: interval,
+		done:     make(chan struct{}),
 	}
 	go urlTest.loop()
 	return urlTest, nil