There is not groundwater exploitation in Hexi area, Nanjing. But land subsidence continues to develop. In order to explore the cause of land subsidence in Hexi area, Nanjing. Methods: Based on the systematic study of hydrogeological and engineering geological conditions. The distribution characteristics and development law of land subsidence, as well as the relationship between land subsidence and groundwater level, soft soil distribution and building load are studied. Furthermore, the causes of land subsidence in Hexi, Nanjing are revealed. Results: The groundwater level in Hexi, Nanjing has been relatively stable in recent 5 years. This is consistent with the condition that groundwater is not exploited. The land subsidence is not affected by groundwater exploitation. Land subsidence is closely related to the thickness of soft soil layer and the density of buildings. On the one hand, the greater the building density, the greater the increase of effective stress of soil mass, resulting in greater land subsidence. On the other hand, pile foundation is usually used for the load of high- rise buildings. And the soil layer is compressed and consolidated under the action of friction. Because the mechanical strength of soft soil layer is lower than that of sandy soil, the land settlement in the area with thick soft soil layer is relatively large. Conclusions: Land subsidence is closely related to the thickness of soft soil layer and the distribution of building load. Land subsidence is mainly affected by buildings engineering. That is, the effect of building load and deep foundation pit dewatering.