The temporal and spatial characteristics and mechanisms of perimeter rock deformation in the three large cavern chambers of Shuangjiangkou Hydropower Station are analyzed, and with the plant cavern as the focus of the study, the monitoring feedback design for monitoring during the construction period was carried out using perimeter rock deformation, support load monitoring data as well as drilling acoustic wave detection data, and by adopting the inversion method of the mechanical parameter that took into account the dynamic evolution of the relaxation zone around the cavern. The results show that: The spatial characteristics of rockmass deformation result from superposition of unloading effect, the cavern group effect and high wall effect with unloading effect as a main factor which result in unsymmetrical deformation of powerhouse; Thanks to the good quality of granite rockmass, the high ratio of rock strength to in-situ stress and scarcity of weak structural plane, the largest peripheral displacement of powerhouse is 28mm; For surrounding rockmass that has been just exposed or merely experienced 2 ~ 3 underlying slicing excavation, the only component of total displacement is excavation induced rebounding deformation; For rockmass that has experienced more than three underlying slicing excavation, time related deformation due to progression degradation of rockmass can be found in total displacement but occupy a small proportion and converge very quickly after the excavation of powerhouse has been finished; In case of time effect existed properly modeling of damaged zone around cavern is necessary and numerical calculation based on such model can give a good prediction of deformation increment. There exists no abnormal deformation in surrounding rockmass when the intensity of rock bolt support is decreased at some important construction stages according to prediction of future deformation, which means that feedback design of support is reasonable.