The concentration of pollution gas at the boundary of industrial parks is not only affected by the discharge of unorganized pollution sources in industrial parks but also by the diffusion of vehicle exhaust gas on roads in industrial parks. The ag-FTIR-DA3000 open-FTIR system was used to measure the polluted gas at the plant boundary in real-time and determine the measured concentration of the polluted gas at the plant boundary. At the same time, aiming at the problem that the diffusion of motor vehicle exhaust affects the concentration of polluting gas at the factory boundary, the concentration of motor vehicle exhaust pollution source with different emission standards is determined by ag-FTIR-DX4000 portable Fourier to transform infrared(FTIR) measurement system. A mathematical model of Gaussian diffusion was established based on the results of portable FTIR measurement, wind speed and direction, atmospheric stability, traffic flow and other variable factors. Combined with the open-FTIR measurement method, the integral calculation of the Open-FTIR measurement path was carried out, and the point-line source diffusion model was constructed to establish the smoke cluster line-source diffusion table of various emission standards. The concentration measured by Open-FTIR was combined with the concentration simulated by the point-line diffusion model to analyze the concentration source at the industrial park’s boundary. The comprehensive analysis results show that other polluting gases at the factory boundary mainly include carbon monoxide, methane, ethylene, acetaldehyde, propylene, methanol, propyl aldehyde, isobutene, formaldehyde and sulfur dioxide. The concentrations of carbon monoxide, methane and ethylene at the boundary are greatly affected by motor vehicle exhaust, and the concentrations of polluting gas at the boundary are greatly affected by motor vehicle exhaust diffusion at the peak time in the morning and evening. Off-peak, the concentration rises sharply at 1:00 and 4:00-6:00, and the high concentration point appears, which is not in line with the motor vehicle exhaust model emission rules, mainly affected by the park emissions. The maximum and average concentrations were 5.50 and 4.00 mg·m-3, respectively. 1.85 and 1.60 mg·m-3; 78.00 and 40.00 μg·m-3.The diffusion concentration distribution results of tail gas are consistent. The highest and average values of other components were 1.65 and 1.40 mg·m-3 respectively. 2.60 and 1.27 mg·m-3; 43.53 and 11.40 mg·m-3; 310.23 and 839.05 μg·m-3; 76.32 and 38.96 μg·m-3; 47.70 and 25.20 μg·m-3; 1.33 and 1.16 mg·m-3. This study not only realized the real-time online measurement of multi-component polluted gas at the boundary of the industrial park but also built a point-line source diffusion model, combined with the field environment and portable FTIR measurement results to achieve the mixed determination of the concentration of polluted gas at the boundary of the factory. It provides an analytical thought for judging the future source of polluting gas at the boundary of the industrial park.