Abstract: Urban land subsidence is liable to induce ground fractures or even collapse,thus causing safety accidents.However,traditional geophysical methods cannot be applied in cities due to the strong human interference and high requirements for safety and environmental protection in the urban environment.The microtremor survey method is a passive,efficient,and environment-friendly geophysical method and it can be used to detect the underground geological conditions in the urban environment with strong interference.Taking Xiegang Primary School in Hefei City as the research site,this paper focuses on the applicability and effectiveness of the microtremor survey method in detecting the causes of land subsidence.Based on the microtremor survey data collected,the dispersion curve was extracted using the F-K method and then the underground shear wave velocity structure was obtained through inversion,thus revealing the underground geological conditions.Finally,verification was conducted through drilling.The results show that the microtremor survey is an effective geophysical method for detecting the information such as the position and scale of underground unconsolidated soil,and thus the secondary accidents in subsidence areas can be eliminated.