In view of the high real-time and multi-task design requirements to UAV simulation system and the problems of complicated manual code development and long design cycle, a design method using RTW and C code on VxWorks platform is proposed.First, Simulink tool is used for developing the UAV simulation system.Then missions of the simulation system are divided into system administration, model solving, scheduling management and interfacing task, which are designed respectively.Then, Real Time Workshop (RTW) is used to compile the Simulink and C code files into an executable file, and thus to implement the construction of the UAV simulation system.Semi-physical simulation results show that:1) The UAV simulation system has proper simulating function and can meet the real-time requirements; and 2) Compared with the traditional manual code development mode, the method based on RTW together with C code reduces system design complexity and accelerates the simulation platform development.