Low-light image intensifier is a key component in night vision technology. The signal-to-noise ratio is one of the important parameters to evaluate the performance of lowlight image intensifier. A control system of signal to noise ratio tester for image intensifier based on FPGA is designed, including signal acquisition module, constant current driving module, main control module, communication module and power module. The system takes XC7K325T FPGA as the core, complete the ADC, DAC, serial communication and other functions as well as interface logic design, realize the photocurrent data acquisition, signal processing and system parameter setting and other functions, so as to complete the measurement of signal to noise ratio of image intensifier. The test results show that the functions of the image intensifier signal-to-noise ratio tester are normal and the measurement error of the signal-to-noise ratio is less than 2%, which verifies the correctness of the design of the control system and lays the foundation for the reliable application of the signal-to-noise ratio tester.