Cognitive radio is a kind of intelligent reasoning learning communication system, and fuzzy Q learning method is introduced to realize the cognitive radio spectrum allocation intelligent learning process. Cognitive users adjust the fuzzy inference system through online Q learning, obtain the optimal fuzzy rules of spectrum allocation and realize the adaptive spectrum allocation scheme. The fuzzy Q spectrum allocation algorithm is compared with non intelligent learning algorithm (fuzzy spectrum allocation algorithm and random distribution algorithm). And the simulation results show that this algorithm improves the system bandwidth income and reduces the system conflict rate.