Abstract: Peer to Peer (P2P) computing technology provides the basic operation facility for collaborations among nodes of open and dynamic network (esp. Internet) and complicated distributed business processing. However, it is difficult to accomplish such works successfully because of some inherent facts of P2P environment, such as peers could randomly join in or quit the P2P network, which make it hard to choose appropriate task undertakers before the project is constructed. In this paper, a flexible and dynamic collaboration alliance mechanism of P2P based on mobile multi-agent technology is proposed. The collaboration alliance mechanism can be deployed in complex and changeful environments to overcome the difficult problem of peers collaboration, which is working as the following ways: driven by one demand, the leader peer constructs the project; after the work undertakers are all selected, the temporary and optimized collaboration alliance is formed; according to the workflow, the leader peer and other work peers collaborate to accomplish the tasks of the project based on their commitments. The mechanism is also utilized to build the agile Supply Chain Management (SCM) system to verify its practical value.