Transactive memory has been identified to describe a shared memory system for group members to store and access group intelligence. With the emerging peer-to-peer (P2P) technology, individuals within and between groups may interact by virtue of the peer-to-peer architecture to mobilize group dynamics. This paper designs the transactive memory on peer-to-peer networks, and then evaluates the effects of P2P transactive memory system. Through simulation, knowledge networks in the community are constructed and the performance of individuals to find, store, apply, and retrieve information is evaluated. The results show the improvement of group performance in the cumulative inquiry rate and learning outcomes. The evolution of peers' knowledge networks is also assessed to understand the effects of P2P transactive memory systems. This study, though using simulation, has shed light on adopting P2P networks to facilitating individuals in a virtual community to share knowledge and collaborate for problem solving.