Based on the images of pollution mass continuously collected in the breaking zone, this paper studied the transport and diffusivity of pollutant in the surf zone under the oblique incidence of regular waves on the plane beach. Firstly, the experiment and image processing methods were introduced, and the centroid point and dispersion degree of the pollution mass were obtained. The transport velocity of pollution mass in the longshore direction and the cross-shore direction were obtained by following the change of centroid point in horizontal two-dimensional space and the alignment fitting. Then the relationship between the transport velocity in the longshore direction and the maximum time-averaged current velocity in the long-shore direction were analyzed. The cross-shore diffusion coefficient was estimated by assuming a Gaussian diffusion process in this study, and five horizontal transport velocities of pollution mass and five cross-shore diffusion coefficients were obtained and analyzed. The results show that the alongshore transport velocity of pollution mass is about 33% of the maximum time-averaged current velocity in the long-shore direction, and the transport velocity as well as the diffusion coefficient in the cross-shore direction is respectively within the range of 0. 008-0. 03 m/s and 0. 16×10^-3-2. 6×10^-3 m²/s.