In order to effectively control the emission of vehicle exhaust, it is necessary to analyse and study the control algorithm of vehicle exhaust emission. When using the current algorithm to control the vehicle exhaust emission, it cannot accurately calculate the ambient air capacity of nitric oxide, hydrocarbons, particulate matter and do not have synergistic control effect. On the basis of mathematical analysis, an intelligent control algorithm for vehicle exhaust emission is proposed. International Vehicle Emissions (IVE) model is used to calculate the emission of pollutants in the running and starting stages of the vehicle, so as to improve the precision of the vehicle exhaust emission. The box model and road traffic model are used to accurately calculate the atmospheric environmental capacity and analyse the pollutant emission reduction based on the calculation results. Through the PID control algorithm, the control of vehicle exhaust is completed and the synergistic control effect of the method is improved.