Abstract: With the development of military technology, satellite communication plays an increasingly important role. Satellite communications has been unable to meet the growing demand and study for finding a communication protocol to meet great of business data is very necessary. A priority and demand based dynamic TDMA (Time Division Multiple Access) protocol is presented and using OPNET software to build an environment to simulate this experiment. The satellite obtains information from each ground station and allot time slot to every ground station dynamically, based on their needs and priority. Simulation results show that, several most important parameters, e.g., end-to-end delay, throughput of system, meet the demand of rapid data communication in space-based tactical network. Therefore, this research for the TDMA protocol has great reference value, on setting up the space-based communications network.