Suitability evaluation of land reclamation is an important prerequisite for determining the reuse of damaged land in mining areas. To make full use of land resources in mining areas and repair damaged land, this study takes four dumps in the eastern part of the arid desert area of northwest China as the research object, and uses the platform and slope as the evaluation unit to consider ecological land as the direction. The indicators affecting the reuse of dumps are selected as five aspects: Terrain conditions, soil conditions, location conditions, irrigation and drainage facilities, and environmental risks. The suitability evaluation index system of land reclamation based on niche fitness is constructed, and the obstacle degree is introduced to diagnose the obstacle factor. The results showed that (1) the niche fitness index of each unit in the study area was between 0.339 and 0.751, indicating that the suitability grade of reclamation for ecological land is typically low. The suitability index of the same dump platform (0.511–0.751) was generally higher than that of the slope (0.339–0.628). (2) Each factor responded differently to the obstacle degree of different units. The slope, gravel content, and drainage conditions are the key elements influencing the slope. The major obstacles for the platform are soil and drainage conditions. In soil conditions, the gravel content and bulk density of the soil are limiting factors of platform. The method developed here can be effectively used to evaluate the suitability of mining areas for reclamation. The results provide a scientific basis for the reclamation and ecological reconstruction of open-pit coal mine dumps in arid desert areas of northwest China.