In order to generate self-check signal and speed instruction of radar antenna system test signals, design a kind of mixed signal generation system based on C8051F206 and FT245R.The system uses FT245R USB chip to realize the communication of upper machine, and rely on C8051F206 high SPC and C language to response the instructions of upper machine in a reliable way and send real-time measured parts required for the self-check instruction,speed instruction,etc.This paper introduces the principle of hardware design and software design of mixed signal systems. Practical application shows that the system can accurately generate radar antenna system self-check signal, speed signal and real-time feedback test results.