Abstract: Traditional network security policy can not prevent attack or identify abnormal behavior of the internal nodes in the sensor network．This paper presented a trust computation model of nodes based on Bayes estimation in wireless sensor networks(Abbreviates as TCM-BE)according to the node resource-constrained characteristics．The direct trust which calculates the expectations of the reputation function on nodes behavior based on beta distribution is priori information and the recommendation information from neighbor nodes as sample information in Bayes estimation method．The simulation shows that the scheme has good stability,can effectively identify abnormal node,thereby can prevent attack from the internal nodes of the network．The analysis shows that compared with RFSN scheme it not only can save storage space and computing time with traffic,but also can avoid the phenomenon of malicious evaluation on the node trust.

Key words: Wireless sensor networks,Trust computation model,Bayes estimation,Priori information,Reputation,Beta distribution