In order to improve the quality of service for network users, the cognitive network and the trusted network provide guarantee mechanisms with intelligence and credibility. On the basis of the intelligent characteristics of artificial immune system, a trusted QoS multicast routing algorithm is proposed based on the asexual propagation optimization under the framework of the cognitive network using technologies of the trusted network. Meanwhile, the sliding window method is used to design the trust evaluation mechanism. It records and evaluates the behavior of each network node in order to keep the credibility of the network. According to the optimization mechanism of asexual propagation, the routing selection is based on the user satisfaction and node trust value, and the optimal solution which satisfies the QoS for users is obtained. Finally, the performances of the proposed multicast routing algorithm and classical multicast routing algorithms are evaluated on the simulation platform. The results show that the trusted QoS routing mechanism can provide better quality of service for network users than the other ones.