In recent years, the strong development on IEEE802.11 wireless network and the peripheral industry, the prevailing use of personal handset devices such as PDA and notebook computers and the strong impetus of government strategies towards electronization and mobilization have gradually changed most people's using habits on information products. But when people enjoy the convenience wireless networks bring, they don't know that they are limited by the infrastructure Mode of wireless network because the nature of short distance and the lacking of hand off mechanism in IEEE802.11 wireless network make the users have to access it near the fixed points. However, in Wireless Ad-hoc Network, all the mobile nodes play the role of routers. Information can be transmitted through the mobile nodes between the origin node and the destination node. In this way, information can even be sent to multiple distances. Thus the Wireless Ad-hoc Network can solve the problem of insufficient distance encountered in IEEE802.11 wireless network. In addition, the Wireless Ad-hoc Network is also excellent to be used in battlefield and for emergency department. This paper will discuss the integration of AODV routing protocol and mobile IP under SIP environment. AODV will be responsible in moving in the sub-network and Mobile IP will be in charge of hand-off mechanism while crossing sub-networks. The mobility and the hand-off mechanism of the above structure will be presented in the way of software simulation and other possible applications will also be further analyzed.