In this paper, new attacks against trust recommendation are identified and relationships between these attacks are analyzed. Then a trust model is presented with recommendation trust revision support based on Bayesian Decision-Making theory and the minimum- loss principle. The proposed trust model with recommendation trust revision (TMRTR) is employed in ad hoc networks for optimizing ad hoc routing. Simulation results in MATLAB environment show the method proposed is helpful to reduce the impact of some new threats to trust management and improves the effect of trust management. Synchronously, the proposed system can effectively detect malicious nodes in ad hoc networks.