Abstract: The surface cracks and wellbore cracking phenomenon have appeared successively in the area of the east and west air shaft well of Chengchao iron mine, and the surface cracks scope is also in the unceasing expansion. It has already threatened the safely of the east and west air wellbore structure. Based on the deformation monitor situation of the wellbore cracking and the surface fissures as well as the scene investigation, the mechanics mechanism of the wellbore structure and foundation deformation was studied. It analyses the causes which results in the surface deformation and the wellbore cracking in the east and west air shaft well area，and obtains the drainage of underground water and underground mining are the direct causes of the surface deformation and the ground subsidence phenomenon, moreover the engineering geology structure and the hydro-geological conditions in the mining area also have influence to the surface deformation characteristic, and some corresponding measures to slow down the surface deformation in the wellbore areas is proposed.

Key words: Underground mining, Surface deformation, Ground subsidence, Wellbore cracking, Surface cracks