diff --git a/.gitignore b/.gitignore
index 77104d20..6b4fd25c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,6 +36,7 @@ public/react/yarn.lock
 /.idea/*
 
 # Ignore react node_modules
+public/system/*
 public/react/*
 /public/react/.cache
 /public/react/node_modules/
@@ -82,4 +83,5 @@ docker/
 educoder.sql
 redis_data/
 Dockerfile
-dump.rdb
\ No newline at end of file
+dump.rdb
+.tags*
diff --git a/Gemfile b/Gemfile
index 281dd705..713eb860 100644
--- a/Gemfile
+++ b/Gemfile
@@ -126,3 +126,5 @@ gem 'request_store'
 gem 'harmonious_dictionary', '~> 0.0.1'
 
 gem 'parallel', '~> 1.19', '>= 1.19.1'
+
+gem 'letter_avatar'
diff --git a/Gemfile.lock b/Gemfile.lock
index cbd598f5..015c0a51 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -162,6 +162,7 @@ GEM
       activerecord
       kaminari-core (= 1.2.0)
     kaminari-core (1.2.0)
+    letter_avatar (0.3.8)
     listen (3.1.5)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
@@ -456,6 +457,7 @@ DEPENDENCIES
   jbuilder (~> 2.5)
   jquery-rails
   kaminari (~> 1.1, >= 1.1.1)
+  letter_avatar
   listen (>= 3.0.5, < 3.2)
   mysql2 (>= 0.4.4, < 0.6.0)
   oauth2
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 30953bf5..18523d70 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -149,12 +149,7 @@ module ApplicationHelper
         File.join("images/avatars", ["#{source.class}", "#{source.id}"]) + "?t=#{ctime}"
       end
     elsif source.class.to_s == 'User'
-      str = source.user_extension.try(:gender).to_i == 0 ? "b" : "g"
-      File.join(relative_path, "#{source.class}", str)
-    elsif source.class.to_s == 'Subject'
-      File.join("images","educoder", "index", "subject", "subject#{rand(17)}.jpg")
-    elsif source.class.to_s == 'Shixun'
-      File.join("images","educoder", "index", "shixun", "shixun#{rand(23)}.jpg")
+      source.letter_avatar_url
     end
   end
 
diff --git a/app/models/concerns/.keep b/app/models/concerns/.keep
deleted file mode 100644
index e69de29b..00000000
diff --git a/app/models/user.rb b/app/models/user.rb
index bf4ec104..20b3a854 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -66,6 +66,7 @@ class User < Owner
   include Likeable
   include BaseModel
   include Droneable
+  include User::Avatar
   # include Searchable::Dependents::User
 
   # devops step
diff --git a/app/models/user/avatar.rb b/app/models/user/avatar.rb
new file mode 100644
index 00000000..4b62c28f
--- /dev/null
+++ b/app/models/user/avatar.rb
@@ -0,0 +1,32 @@
+require 'letter_avatar/has_avatar'
+
+class User
+  module Avatar
+    extend ActiveSupport::Concern
+    include LetterAvatar::HasAvatar
+
+    def name
+      lastname.blank? ? login : Pinyin.t(lastname)
+    end
+
+    def letter_avatar_url(size = :lg)
+      avatar_url(avatar_size(size))
+    end
+
+    # 返回头像尺寸
+    # xs: 22px
+    # sm: 32px
+    # md: 48px
+    # lg: 120px
+    def avatar_size(size)
+      case size
+      when :xs then 22
+      when :sm then 32
+      when :md then 48
+      when :lg then 120
+      else size
+      end
+    end
+
+  end
+end
diff --git a/config/initializers/letter_avatar.rb b/config/initializers/letter_avatar.rb
new file mode 100644
index 00000000..88f3851e
--- /dev/null
+++ b/config/initializers/letter_avatar.rb
@@ -0,0 +1,7 @@
+LetterAvatar.setup do |config|
+  config.fill_color        = 'rgba(255, 255, 255, 1)' # default is 'rgba(255, 255, 255, 0.65)'
+  config.cache_base_path   = 'public/system/lets'     # default is 'public/system'
+  config.colors_palette    = :iwanthue                # default is :google
+  config.annotate_position = '-0+10'                  # default is -0+5
+  config.letters_count     = 2                        # default is 1
+end