The article firstly reviews the evolution of the 1st generation (analogy) mobile communication system and the 2nd generation (digital) mobile communication system, and predicts that deployment of mobile communication systems will be enter a development period at a more great rate in the next decate. The mobile communication service will extend from voice to data, and the mobile communication technology will transits from circuit mode to packet mode. Following briefly addressing the second and half generation mobile communication system (2.5 GM) that will come to application soon, introduces the 3rd generation mobile communication (3 GM) for broadband multimedia application. Some schemes as mainstream of 3GM RTT (radio transmission technology) standards and the key technologies, especially technical features of TD - SCDMA presented by China, are emphatically described. Finally, The transition strategy from 2GM to 3GM and the development trend of 3GM core network are prospected in this article.