diff --git a/index.js b/index.js
index 061afe5..a28406f 100644
--- a/index.js
+++ b/index.js
@@ -12,6 +12,7 @@ const DEFAULT_CONFIG = {
   ttl: 3600 * 24 * 7,
   domain: '', // NODESSID域, 默认等于domain
   level: 0, // 校验级别, 0: 不校验客户端, 2: ua, 4: ip, 6: ua + ip
+  secret: 'it_is_secret_key', // jwt密钥, 使用时请修改
   db: {
     host: '127.0.0.1',
     port: 6379,
@@ -23,8 +24,12 @@ const DEFAULT_CONFIG = {
 export const SessionModule = {
   name: 'session',
   install(conf = {}) {
-    if (!conf.domain) {
-      throw new Error('Please make sure to set the `domain` field')
+    if (!conf.secret) {
+      console.warn(
+        new Error(
+          'You must set a `secret` key for session, or it will use the default key.'
+        )
+      )
     }
     let session = Object.assign({}, DEFAULT_CONFIG, conf)
     this.set({ session })