In order to solve the problem of long-time input of piston engine parameters in UAV semi physical simulation experiment, a lightweight portable multi-sensor signal simulation system is proposed. Firstly, the three-level structure of touch screen man-machine/MCU/signal simulation module is designed and realized. Taking a certain piston engine as the simulation object, a signal simulation system is built, which can simply and conveniently realize the scheduled output of various parameters. The circuit simulation method is designed, which can simulate thermal resistance, thermocouple, 4~20 mA current signal, speed pulse signal and switching value signal. The error of some easily disturbed signals is analyzed, the error calculation formula and error value estimation are given, and the feasibility is verified. The system can replace the engine as the signal source of each long-term test, which not only greatly saves the test cost, but also helps to further expand the test boundary.