Abstract: Chengchao Iron Mine of Wuhan Iron and Steel Corporation was taken as the engineering background. Drilling monitor and similar material model test were used to study the regular and mechanism of capping rock collapse during orebody caving. Firstly, based on the condition of orebody occurrence, strata's structure and mining process, two drill-holes were designed to monitor the protess of capping rock collapse. Secondly, based on the similar model theory, according to sections and geometry sizes a similar material model was built to study the characters of strain, displacement and deformation through the data collection methods of pressure cells, percent meters and photogrammetry. The collusions reveal the elementary mechanism of capping rock collapse and the rules of ground subsidence during the caving process by non-pillar sublevel caving.