In order to clarify the optimal reconstruced soil characteristics for vegetation growth in grassland mining areas, No.1 open-pit coal mine in Shengli Mining District of Beidian, Inner Mongolia was taken as the study area. Different methods of soil reconstruction and maturation were set up. Then soil bulk density, organic matter content, total nitrogen content, available phosphorus content, available potassium content, field water holding capacity and pH value were selected to establish a comprehensive soil fertility evaluation system. The spatial variability characteristics and distribution pattern of biomass and comprehensive fertility index were determined by the combination of GIS and geographical statistics. The results show that the soil fertility index will be the best when the soil reconstruction method is that the mixture ratio of rock and soil stripped material, coal gangue and fly ash in the surface layer of 50 cm is 3 ∶ 4 ∶ 3, and the lower part is the natural accumulation of mining stripping. The maturation method has little effect on the soil fertility. The vegetation grows best when the soil reconstruction method is that the mixture ratio of soil stripped material, coal gangue and fly ash in the surface layer of 50 cm is 3 ∶ 4 ∶ 3, and the maturation method is that plow and plant alfalfa in that year, turn alfalfa into soil and plant alfalfa again by the end of the year.