Abstract:The high-intensity mining of coal mine has caused a large area of subsidence area, accelerated the weathering of the soil, and then caused heavy metal pollution of the soil, seriously affecting the ecological environment of the mining area. This paper in Fengfeng coal mining subsidence As the research object, the selection of typical soil profile, through the analysis of different depth of soil heavy metals (As, Cu, Ni, Pb, Cr, Cd, zinc, and Hg) distribution, chemical weathering regularity studies using the theory of mass balance, driven by exploring collapse section soil heavy metals chemical weathering process, the results show that the typical profile in Fengfeng coal mining subsidence of soil heavy metal element content of Pb, Cd and As more than national standard of controlling farmland soil pollution risk, the biggest overweight multiples, respectively 3.86 times, 59.77 times, 3.82 times; Heavy metal elements Cu, Ni, Zn, Cr and Hg have not exceeded the standard. Heavy metal elements Cd and As may be driven by collapse and influenced by surface runoff and rainwater leaching and infiltration, making their content gradually increase from the surface layer downwards. Surface soil elements Cu, Pb, Cr and Hg were enriched by migration, while Ni, As, Zn and Pb were leached out. The removal and leaching of Cu, Ni, Zn and Pb from the bottom layer of the plough, and the migration and enrichment of Hg showed no obvious changes in other elements. Cumulative elements have potential risks and need to be monitored; The leached elements present a direct risk and need to be highly controlled. This experiment provides scientific basis for comprehensively evaluating the influence of coal mining on soil chemical properties, preventing soil erosion in watershed and protecting regional ecological environment.