In order to study the self-healing process of asphalt, in molecular dynamics, the model of asphalt and the crack model were established by four-fraction analysis method. The diffusion process of the four fractions in the healing process was simulated with different temperature, pressure and aging content. The density and mean square displacement curves of the healing model were obtained and the diffusion coefficients of the healing stage were calculated. The results show that the self -healing process of asphalt can be divided into three stages of density recovery stage, structure recovery stage and self-diffusion stage; the diffusion coefficients of asphalt in the process of healing are ranked in the order: saturates>aromatics>asphaltenes>resins; in asphalt healing, temperature and pressure increase can promote the movement of asphalt molecules; in the same condition, the diffusion coefficient of aged asphalt healing is obviously lower than that of unaged asphalt. Among the four fractions of asphalt, the diffusion of resin during healing is least affected by environmental changes.