An improved spectrum sharing model was proposed in cognitive radios.The improved model considers com-prehensively impact on the primary users’ profits by all secondary users’ bandwidth requirement

and impact on every secondary user’s profit by other secondary users’ bandwidth requirement.Meanwhile

primary users in competition with secondary users can gain maximum profits by finding the optimal price of bandwidth

secondary users compete or coop-erate with each other can gain maximum profits by changing the required spectral bandwidths in limited spectrum.The simulation on features of this improved model

such as static game

dynamic game and its stability

Pareto optimal

has proved that this model adapts to the actual situation.