In hardware-in-the-loop simulation system of missile, accurate timing and data synchronization are key factors for guaranteeing performance of real-time system.The traditional Windows operating system brings many uncertain factors to the Hardware-in-loop simulation test due to limitation in real-time function.In this paper, RTX based on Windows platform was introducesd as one solution of strong re-al-time system.It realizes data interaction between RTX and Windows processes through the method of shared memory, and the subsystem softwares were completed by MFC based on VC++6.0.The proposed method has been applied in missile hardware-in-loop simulation test.The test results are consistent with theoretical calculations, demonstrating the whole system is reliable and stable.As a result, the method proposed in this paper can satisfy system requirements of real-time and accuracy.