Abstract: Based on Chengchao Iron Mine of Wuhan Iron and Steel Company,which uses pillarless sublevel coving mining mothod, as the engineering background, using GPS survey and leveling survey to establishment a surface subsidence monitoring system which has 193 horizontal displacement monitoring points as well as 95 settlement points, monitoring the center of collapse areas and surrounding areas for a period of 12 months, especially to analysis the settlement, developing process of settlement crater profile, deformation of the mine key structures, the extended relational between surface moving boundary with time and underground goaf.The general law and characteristics of surface subsidence are summarized.

Key words: Pillarless sublevel coving mining mothod, Ground subsidence, GPS survey, Movement scope, Deformation and failure