Relevant studies have shown that in the exhaust gas of motor vehicles, particles with a particle size range of 10-500nm can penetrate the alveoli and enter the blood circulatory system after entering the respiratory system, posing a serious threat to human health. Approximately 450,000 people die in Europe each year. Caused by heart disease or cancer. Although the installation of particulate matter post-treatment facilities (DPF/GPF) on motor vehicles can effectively reduce the concentration of particulate matter, as motor vehicles increase in driving years, various post-treatment facilities will inevitably reduce purification efficiency due to aging and blockage. . Therefore, in order to strengthen the emission control of in-use vehicle exhaust, new periodic technical inspection (NPTI), which uses the purification efficiency inspection of the in-use vehicle DPF, SCR and other post-processing facilities as a means, has received more and more attention. European countries have successively introduced a series of NPTI test specifications and standards, and this has further promoted the development and manufacturing of new exhaust gas detection equipment that can adapt to new test requirements.