Abstract: The stability of stope roof related to mine safety and economic benefits, but also was the primary reason for choice of mining methods and the approach of controlling ground pressure. Study on the law of stope roof collapse, for incense characteristics and scope of xianglushan tungsten ore mined-out area. mathew stability graph is used for ascertainment the hydraulic radius of stope roof continued collapse. and obtainted the critical threshold of stope roof under different span. the mine safety has provided an important basis for exploitation of information and evidence.