Abstract: A subsidence crack was found on the surface of a mining area，and the subsidence range and subsidence volume were expanding. In order to control the ground subsidence crack，the microdynamic detection method was used to predict the underground space. By arranging the microtremor survey results of 8 exploration lines and 53 physical points，the Vs profile diagram in the area is measured. The Vs profile dia⁃ gram is interpreted in combination with the geological profile，and the location of the ground fissure is de⁃ termined by the inversion method. The research shows that the microdynamic detection method has high ap⁃ plicability in the ground research of goaf，and the result is basically consistent with the drilling results.

Key words: the microdynamic detection method, underground goaf, physical detection