In order to investigate the diffusion law of heavy metal pollutants in soil, the paper deduced the effect law of space, time and diffusion coefficient on the pollutant concentration of heavy metal around the buried point based on three-dimensional diffusion equation.It also analyzed the influence of differences between two buried methods such as namely centralized and decentralized buried approaches on pollutant concentration distribution of heavy metal.The results show that when the other conditions are the same, the concentration of a spatial position increases first and then decrease with the increase of both diffusion time and diffusion coefficient,and Finally the curve tends to be gentle; when the diffusion time keeps constant, the concentration decreases with the increase of diffusion radius, and trends to zero at the end. After comparing three different buried methods, it found that the fewer the buried points, the higher the nearby concentration, and the more buried points, the lower the concentration at far positions.