Tunable semiconductor laser absorption spectrum technology (TDLAS) has the characteristics such as high resolution and high sensitivity, currently widely used in trace gas detection, so portable and online debugging is the trend of its development. Because the FPGA has the obvious advantages of fast speed, small size, simple structure, strong anti-interference ability, online debugging, parallel and so on, combined with FPGA technology, TDLAS trace gas detection system will have a good application prospect. This paper mainly studies the signal generation and the signal acquisition based on FPGA. Continuous observation experiment in the open light path indicates that the signal is high precision and its frequency can be as high as 10 kHz without distortion, the acquisition is high precision, stable and reliable, optimizing the traditional TDLAS trace gas detection system. It can be seen that the FPGA implementation of signal generation and signal acquisition is feasible, which is an important step to the FPGA implementation of TDLAS trace gas detection system.