In China,the mined-out areas in metallic and nonmetallic mines is very large in scale and is complicated,so there is great hidden safety dangers due to the existence of these mined-out areas.According to the investigation on mined-out areas in large-scale and medium-scale metallic and nonmetallic mines(or mining area) in China,the actual state and hazards of the mined-out areas,existing problems and the causes of problems are analyzed.It is pointed out that the hidden safety dangers due to continuous extents of mined-out areas in building materials mines and chemical mines is most serious,large-size and medium-size mined-out areas mostly exist in nonferrous metals mines and metallurgical mines,the hidden safety dangers due to mined-out areas is most serious and the treatment of mined-out areas is difficult in hot spots for mining,it is the key for treatment of mined-out areas to make relevant policies and establish incentive mechanism.The countermeasures and measures for the treatment of mined-out areas are discussed in three aspects of policy orientation,technological support and treating measures.