Due to the success of Napster, Gnutella and Freenet, peer to peer (P2P) computing has suddenly emerged at the forefront of Internet computing. And a lot of problems including security, reliability and rooting are urgent to be solved.Unfortunately, traditional techniques are not directly applicable to P2P systems. This paper presents a new framework called MAPPS for designing P2P applications based on JXTA and mobile agents. The MAPPS framework is structured as three layers:the MAPPS infiastmcture based on mobile agents, MAPPS services and MAPPS applications. In this way, MAPPS not only follows the ootstanding architecture of JXTA, but also enhances the mobility and flexibility of P2P systems. Using MAPPS,developers of new P2P systems can design and implement P2P systems more efficiently.