This paper proposes a trust ant col-ony routing algorithm by introducing a node trust evaluation model based on the D-S evi-dence theory into the ant colony routing proto-col to improve the security of wireless sensor networks. To reduce the influence of conflict evidences caused by malicious nods, the con-sistent intensity is introduced to preprocess conflict evidences before using the D-S com-bination rule to improve the reliability of the D-S based trust evaluation. The nodes with high trust values will be selected as the routing nodes to insure the routing security, and the trust values are used as heuristic functions of the ant colony routing algorithm. The simula-tion tests are conducted by using the network simulator NS2 to observe the outcomes of performance metrics of packets loss rate and average end-to-end delay etc. to indirectly evaluate the security issue under the attack of inside malicious nodes. The simulation results show that the proposed trust routing algorithm can efficiently resist malicious attacks in terms of keeping performances of the average end-to-end delay, the throughtput and the routing packet overhead under attacking from mali-cious nodes.