Real-time test platform based on hardware-in-the-loop (HIL) simulation technology, troubleshooting for real-time problems such as interrupt latency and interface communication before physical testing, can effectively improve the traditional development process, shorten the research and development cycle, and reduce the cost and risk of test. Based on the technologies of virtual instrument, mathematical modelling, and HIL simulation, a real-time simulation framework combining the discrete-time converter system and the continuous-time motor system is proposed. Combined MATLAB/Simulink, dSPACE, and real-time hardware, an HIL real-time test platform is designed for the prototype and proper testing of the electrical control unit of more electric aircraft. The results and design principles of a three-stage brushless synchronous starter/generator system emulation using HIL simulation are presented.