The stability of the surrounding rock mass around cross tunnel in the right bank slope of Dagangshan hydropower station, in the southwestern China, was analyzed by microseismic monitoring as well as numerical simulations. The realistic failure process analysis code （abbreviated as RFPA3D） was employed to reproduce the initiation, propagation, coalescence and interactions of micro-fractures, the evolution of associated stress fields and acoustic emission （AE） activities during the whole failure processes of the surrounding rock mass around cross tunnel. Combined with microseismic activities by microseismic monitoring on the fight bank slope, the spatial-temporal evolution and the micro-fracture precursor characteristics during the complete process of progressive failure of the surrounding rock mass around cross tunnel were discussed and the energy release law of the surrounding rock mass around the cross tunnel was obtained. The result shows that the precursor characteristic of microfractures occurring in rock mass is an effective approach to early warn catastrophic damage of rock mass around cross tunnel. Moreover, the heterogeneity of rock mass is the source and internal cause of the failure precursor of rock mass.
