Social network has already been an important way to facilitate information exchange.One key challenge in social network is how to evaluate the reliability of users complex relationships.In this paper,we propose a complex trusted path-based algorithm for computing trust.Our main works are (1) we consider the users in social networks as vertices in a graph; (2) complex path composition in SNS is proposed according to its topology,and (3) an approach of computing complex path trust is proposed based on its topology.