For treating the coal mining subsided area, coal gangue is usually used to filling the subsided area and topsoil will be covered to reclaim, then the abandoned land will be used to plant crops, but different topsoil thickness will influence the nutrient content and the yield of crop. Xinzhuangzi coal mine reclamation land is chosen and different thickness topsoil is sampled to analyze the soil quality. The texture, organic matter, available nitrogen, available phosphorus and available potassium are detected, the results show that soil nutrient is rising with the increasing of topsoil's thickness from 40cm to 75cm, after the topsoil thickness is exceeded 75cm, there are no significant nutrition and crop yield increase. The experiment shows that best covering topsoil thickness is 75cm, and reasonable fertilization and irrigation can help the reclamation land to renew fertility.