With the increasing number of vehicles, the harm from vehicle exhaust to the environment becomes more and more serious. So the monitoring of the concentration of vehicle exhaust emissions is very important to assess the emission levels. The NO and NO2 quantitative detection system based on nondispersion ultra- violet (NDUV) for vehicle exhaust emissions is built, and the original data of the mixed tail gas is obtained. And then, the identification and quantitative analysis of NO and NO2 gas is carried out with fast independent component analysis (Fast ICA) and artificial neural network (ANN) recognition algorithms. It can be drawn from the results that using the two algorithms, the NO concentration (under 600 ppm) and NO2 concentration (under 200 ppm) can be detected accurately and the maximum relative error is 1.54%, and the minimum is 0.25%.