Abstract: As a result of its significant advantages of high efficiency and remote imaging detection, gas leak infrared imaging detection technology has become one of the most effective means to detect gas leaks. This paper focuses on the performance measurement system of gas leak infrared imaging detection system. A novel minimum resolvable gas concentration(MRGC) evaluation method was proposed that was suitable for evaluating the performance of the passive gas leak infrared imaging detection system. The MRGC measurement system was designed and built. The measurement result, using ethylene as the target gas, and the minimum resolvable temperature difference (MRTD) curve were in good agreement, which sufficiently demonstrated the effectiveness of the MRGC performance evaluation method.