With the rapid development of science and technology, motor vehicle technology is also undergoing reform and innovation, and the driving safety is the most important issue[1]. In order to strictly control the safety of motor vehicles, the production plant, testing station and maintenance plant are all equipped with headlamp testers for motor vehicle (hereinafter referred to as a light tester) to detect the lighting performance of motor vehicles [2]. It is especially important whether the light tester is qualified or not and whether the deviation is large or not. Based on the JJG745-2016 "headlamp testers for motor vehicle ", this paper uses the motor vehicle’s headlamp tester near and far light calibrator as the standard, and evaluates and discusses the uncertainty of measurement error of far light intensity indicator in headlamp testers, so as to provide reference for the calibration of the light tester.