Abstract: Illegal mining has a great influence on stability of mines. Based on the prototype of the representative metal mine, two-dimensional physical simulation model test on an underground iron mine is carried out. The regulations of surface deformation and surrounding rock movement with or without illegal mining are obtained respectively. Results obtained indicate that when ore between –270 m and –550 m are excavated, the subsidence of surface and deformation of surrounding rock increase slowly. But when ore below –550 m are excavated, the subsidence of surface and deformation of surrounding rock increase quickly because the obliquity of orebody become smaller. Because of stress redistribution caused by illegal mining, the size of surface subsidence increases near surface gob and horizontal displacement of surface increases greatly; but the range of surface subsidence almost has no change.

Key words: model test, illegal mining, underground mining, rock movement, open-underground combined mining