Abstract: According to the geological environment characteristics of the study area, seven indexes are selected, including geomorphic types, surface slope, groundwater depth, groundwater corrosivity, foundation bearing capacity, soil compression modulus and geohazard susceptibility, to evaluate the suitability of construction land in the main urban area of Mudanjiang City based on analytic hierarchy process(AHP) and geographic information system (GIS) spatial analysis. The results show that the suitability of construction land in the main urban area is good, with the suitable and relatively suitable areas accounting for 58.2% of the total area, and the geological environment in the south of the main urban area is the most superior. Thus it is suggested that Mudanjiang City develop moderately to the south, and protect the ecoenvironment and permanent basic farmland.