Abstract: This paper analyses the characteristics of geology and deformation, filling at sliding zone, mechanical parameters of the fracture plan and slip surface of the fracture in the creep rock mass zone B at Longtan hydropower station in Guang-xi province. The analysis is combined with monitoring data, rock weathering, structural feature of slope and slide-tow of slope surface rock mass. The paper draws the conclusion that the cause of fracture plane and slide surface of the fracture was due to a combined effect of the slope lithologic, the erosion by water, and the different weathering characteristic of different rock masses. The analysis of monitoring data also shows that the slope deformation value was little, the deformation trend was not obviously and the slope was stable.