With the integration of telecommunications network and Internet, mobile Internet is bound to rise. Mobile Internet brings not only high-quality business experience; but also enormous challenges to telecommunications. The current status and hierarchical structure of the mobile Internet are presented. Technological advances and market demand are promoting development of mobile Internet, and terminals, networks and businesses are three elements of the development of the mobile Internet. Mobile IP technique and related protocols are described systematically, which are designed to allow mobile terminal and the mobile sub-network to roam within the Internet. Then the IP Multimedia Subsystem (IMS) and its architectural framework are expounded, which are designed by (3GPP). The credible and reliable IP network architecture with Quality of Service (QoS) based on IMS is discussed to meet the needs of the next generation of mobile Internet. Finally, the hotspots such as P2P/ Multicast/ Security are pointed out within the mobile Internet. With the integration of telecommunications network and Internet, mobile Internet is bound to rise. Mobile Internet brings not only high-quality business experience; but also enormous challenges to telecommunications. The current status and hierarchical structure of the mobile Internet are presented. Technological advances and market demand is promoting the development of mobile Internet, and terminals, networks and businesses are three elements of the development of the mobile Internet. Mobile IP technique and related protocols are described systematically, which are designed to allow mobile terminal and the mobile sub-network to Then the IP Multimedia Subsystem (IMS) and its architectural framework are expounded, which are designed by (3GPP). The credible and reliable IP network architecture with Quality of Service (QoS) based on IMS is discussed to meet the needs of the next generation of mobile Internet. Finally, the hotspots such as P2P / Multicast / Security a re pointed out within the mobile Internet.