With the popularity of Android smart phones, all kinds of mobile online games have sprung up like mushrooms. As online card games are a kind of virtual reality simulation system which has the strong ability to create a game environment with immersive realistic scenes, online card games are getting increasingly popular and have been widely played, especially among middle-aged men. The paper introduces some key technologies for implementing a mobile online card game based on Android called Texas Hold'em Poker. The game adopts three layers of C/S model to complete the construction of the system and uses MySQL as the database. In the client, not only are some nice interfaces and animations based on 2D graphics presented, but also the steps to realize them are described in detail. Meanwhile, a multiplayer server is constructed by means of SmartFoxServer2X engine, which has a strong ability to support large-scale concurrent user access. In particular, the concepts called Lobby, Zones and Rooms are established, which allow to organize Zones into Lobby as well as organize Rooms into Zones. One Zone represents a kind of card game and one Room stands for a poker table. Programmers could develop other card games by referencing techniques written in the paper and then add them into Lobby.