To design a commonly-used radio navigation signal simulator,and realize the miniaturization and digitization of test equipment of microwave landing system,a programmable and real-time microwave landing system signal simulator was designed based on Field Programmable Gate Array (FPGA).The simulator uses FPGA as the main control chip.Signal parameters are obtained by serial port communication with PC software.Digital baseband signal is generated by FPGA,and signal simulation is realized through the high-performance analog-to-digital converter AD9777 and the broadband quadrature modulator ADL5375.The realization of microwave landing system signal by FPGA is studied thoroughly,including the solution to the difficult problems in FPGA implementation and the key technologies.The design has been verified by Modelsim 10.1a,and the test results show that the design of signal simulator achieves the expected effect.