Abstract: With rapid development of the technologies and the standard of the third generation mobile communication,third-generation mobile telecom system have been one of the new and the hottest research spot in the communication field of the world.In the paper,the development of the mobile communication technology is introduced,and analyzes network architecture and protocol in the three 3G systems.The mainly technology question of the mobile communication in the construction is discussed. Finally,some key technologies of further development of mobile communications are discussed.