Abstract: To grasp the distribution law of particulate matter at an intersection, by collecting the concentrations of particulate matter at many intersections in Beijing and further analyzing the correlation between particle concentration and traffic characteristics and fitting estimation of data, a spatial diffusion model of particulates at the intersection was established. Finally, the distribution of particles at the intersection of urban roads was obtained. Results show that the distribution of particulate matter on the cross section of the intersection is higher in the center and then decreases to the two sides. The higher the concentration of particulate matter at the point near the intersection parking line is, the greater the fluctuation is. The fluctuation of the particle concentration on the sidewalk is higher than that on the driveway. The regularity of PM_2.5 in particulate matter is consistent with that of PM₁₀ in particulate matter.