Abstract: It is well known that the Guard channel is an important method for the mobile communication systems, which can greatly improve the system performance by decreasing the probability of forced termination. Guard channel is hard to be adopted in the terrestrial communication system because of unpredicted traffics. We change the strategy based on the characters of LEO satellite and get a good performance. Moreover, the queuing of the new traffic has been taken to improve the performance of the whole LEO satellite communication system.