Hardware-in-the-loop communication equipment simulation is an important step of the development about communications and electromagnetic environment simulation. Reference to the "software radio" design thinking, the source library is generated by the software and different communication signals are generated by the fixed hardware frame. The system achieves “versatility”. GMSK in wireless communications has been widely applied. It is one of the important signals generated by the simulator. Based on analysis of the structure, the paper introduces the design of the simulator. It also provides the software simulation of Matlab. It provides a reference simulation for communications equipment and electromagnetic environment simulation.