Under the condition of extremely low illumination， the images collected by the low-light CMOS image sensor generally has the problems of excessive noise， deviation of brightness， and difficulty in updating the system program after assembly. In view of this， a low-light-level imaging system，including hardware and logic， was designed and built， by using an image signal processing module with FPGA as the core， and combining with image acquisition module， interface module， optical lens， GAMMA correction， image filtering processing algorithm and MultiBoot. Related experimental results showed that the low-light-level imaging system could control the low-light-level CMOS image sensor through FPGA to collect low-light images under different illuminations. The host computer could use the serial port to update the FPGA program through the online loading function. It was testified that in the environment of 0.001 lux， the output low-light image resolution was not less than 1.0 mrad， the image could realize information interpretation， and the results could help solve the problem that the human eye could not obtain information at night.