Abstract: In the mobile ad hoc networks, the reliability of service composition is always less than the one in static network environment because of the mobility of nodes and the dynamics of network topology. In order to improve the reliability of service composition, current research works mainly focus on minimizing times of interruption and the services re-composition, and pay little attention to estimating the reliability before composition. By taking advantages of the mobility prediction for mobile nodes, this paper proposed approaches to find the service composition scheme with low failure risks before the composition is performed. It proposed a failure risk model to estimate the reliability of service composition, and then presented three algorithms for performing service compositions based on the reliability estimated. Finally, by comparing with the optimal scheme, we conducted experiments to evaluate the features of our methods.