Abstract: The paper proposed a cross-layer routing selection algorithm, which considers the shortest delay and highest security as routing selection standard. The routing algorithm aims to solve the problem of both the dynamic spectrum and security problem in cognitive radio networks.The Algorithm reduces the data transfer delay by optimizing the number of forwarding nodes and selecting channel for transmitting and receiving, and ensures routing security by choosing a forwarding node of high level security. The results of theory analysis show that the algorithm is efficient and feasible.The computing complexity of the algorithm is O(N2)，where N is the number of nodes in the network topology graph.

Key words: Cognitive radio networks, Cross-layer routing selection algorithm, Sccurc routing, Shortest delay