Abstract: Regarding the network instability of the cognitive mobile ad hoc, which is caused by the mobility of the cognitive user (CU) and the prioritized communication of the primary user (PU), a computational formula of the neighborhood topology maintenance time is established based on the improved mobile model to forecast the average link expiration time using the principle of probability. The topology generation algorithm is designed with the thought of maximum spanning tree, and the topology reconstruction is designed with the neighborhood topology maintenance time as the cycle period. This algorithm is proved to ensure the network connection and distributed operation . The simulation result shows that this algorithm simplifies the network topology, has cognitive ability for PU, effectively decreases the topology reconfiguration and route consumption caused by link broke and improves the end to end network efficiency.