With the development of communication systems, the integration of terrestrial communication systems and satellite communication systems is put forward to provide better quality of communication services. When users are communicating by the satellite communication systems, considering the characteristics such as high-speed of the satellite, the call access and switching problems are impossible to avoid, so it is necessary to study the technologies about access and handover to the terminals that are communicating depending on the satellite communication system. Because the world integration information network should be able to support the communication requirements of multiple scenarios and multiple services, it is important to distinguish different calls by their characteristics. According to their different types, multiple priorities are utilized to classify those calls and then channel allocation strategies are researched in this scenario. The dynamic channel reservation strategy is studied and simulated under the multi-priority.