Abstract: With the increasing number of motor vehicles, exhaust pollution has become the focus of attention, and it is crucial to scientifically manage the excessive emissions of motor vehicle exhaust pollutants and strengthen motor vehicle exhaust detection. The remote sensing measurement system of vehicle exhaust combined Tunable Diode Laser Absorption Spectroscopy (TDLAS), Differential Optical Absorption Spectroscopy (DOAS), and automatic identification technology, which can realize online remote sensing measurement of exhaust pollutant concentration during the driving process of motor vehicles without affecting the normal driving conditions. To fulfill the requirements of JJF 1835-2020 “Calibration Specification for Remote Sensing Measurement Systems of Vehicle Exhaust”, a new auxiliary device for calibration has been developed, which is used for static and dynamic calibration of gas measurement indication error with standard gas and has achieved good results. This paper comprehensively introduced the working principle, device composition, and software and hardware design of the auxiliary device for gas calibration.