Abstract: To resolve the“free rider”and the“tragedy of the commons”problem in peer-to-peer storage systems. In this paper, we propose incentivemechanism in aP2P storage sharing system based on the genetic algorithms. In this mechanism, the provider allocates the sharing space based the genetic algorithms, and maximum its contribution by choosing the optimum policy. The more contribution and themore sharing storage which its can use. Analyses and simulations show that the genetic algorithms-based P2P incentivemechanism is fairness and effective, and itcan discard the free- rider from P2P system effectively and encourage the node sharingmore storage so that itcan earnmore reward.