Peer-to-Peer (p2p), as an emerging technology, is exerting huge influence on various application scenarios. Meanwhile, agents, assisting applications in traditional paradigm with intelligent ways, have to fit in this new trend. Observing the potential benefits of combining agent and p2p technologies, we propose a novel platform-"A-peer" in our approach. A-peer is an agent based secure p2p platform which empower agents to be deployed in p2p environment. In this paper, we define the agent properties and mainly describe its protocol design, essentially agent transmission protocol, agent discovery protocol and agent messaging protocol. We also discuss the security aspect of the platform. Our implementation is based on Aglets system [2] and JXTA platform [1]. A-peer could be efficient for agent based p2p programming for distributed computing, decentralized collaboration, information searching and retrieval, and E-business.