The accumulation of pollution particles on insulator surface can reduce the insulation property of insulator string, which may result in pollution flashover accident of power transmission lines. This paper conducts modeling and analysis work to study the collision deposition process of contamination particles on composite insulator surface. By analyzing the adhesion force in the collision process, the damping force caused by the viscoelasticity of surface material, the energy loss in the first collision contact and the size of contact circle during collision, the stress distribution is obtained. The collision separation point is calculated through the motion equation of the collision process, and the critical velocity of the collision separation is obtained based on the energy conservation law. A particle collision deposition model is established by considering the factors of contact circle size, particle collision deformation, particle critical velocity and rebound velocity. Based on the proposed model, mathematical simulation is carried out, and the influence of wind speed on the deposition of pollution particles on composite insulator surface is analyzed. Finally, the rationality of the model is demonstrated by comparing with the existing wind tunnel test results, which provides a reference for the study of composite insulator surface pollution deposition mechanism.