The invention discloses a cross-layer routing method utilized in a cognitive radio cellular network and based on energy optimization and network lifetime, and relates to the cognitive radio field in wireless communication technology. The cross-layer routing method has the advantages that new routing metrics are provided specific to characteristics that various cognitive users in the cognitive radio cellular networks have different dynamic spectrum resources and energy of wireless cognitive nodes is limited, route selection and channel assignment in the cognitive network are considered in a combined manner by the aid of a cross-layer technology, a priority algorithm for the shortest path is modified, the problem that load on individual nodes is excessively high, energy is used up in advance and the individual nodes fail are solved, death time of each node is delayed, the lifetime of the network is prolonged, large quantities of relay nodes can be selected as cognitive nodes owing to large quantities of available effective nodes, accordingly, the average energy consumption is reduced integrally, and a communication access success rate is increased.