With the development of city construction and economy, emergency departments of the government like the public security system are bearing heavier burdens of large-scale security service and social stability maintenance. The new situations and mission put forward higher requirements that wireless telecommunication should work well in spite of weather and regions in emergency commanding and scheduling. Heterogeneous networking system of digital trunking and satellite communications is needed to expand the coverage of emergency commanding network into areas which can’t be covered by simple systems, such as remote mountains and forest, earthquake-stricken area and so on. Now, emergency communication systems based on satellite link are faced with oversized terminal and portable problems. Furthermore, because the actual coverage capacity of communication satellites are not taken into enough consideration for some systems, the problem of the all blind areas of emergency communication systems still can’t be solved which seriously limits the popularization and application of relevant devices. A digital trunking heterogeneous networking system based on portable satellite station is designed, which greatly reduces costs of the traditional vehicle-borne satellite communication earth station and also solves the blind problem of inaccessible areas for vehicle. Then field tests of this system are carried out under various typical emergency communication application scenarios, which fully proved the feasibility and reliability of the system.