Based on 17 year monitoring data of the Three Gorges Project (TGP), the change laws of deformation, seepage flow and pressure, as well as stress and strain of the main structures in the period of construction and operation are discussed. Meanwhile, the operational status and safety features of various structures in different construction stages and under different circumstances are analyzed and evaluated in detail. The monitoring results show that the repeated rise and fall of reservoir water level affect the deformation of dam in storage and operation stages; the leakage of dam foundation reduces gradually; the high intensity excavation unloading influences the deformation of high rock slope significantly. After the excavation, the deformation of high rock slope rapidly decreases,while the deformation of ship lock is small,but they all vary with temperature obviously. It is concluded that the safety indexes of TGP are within the allowable range of design and the structures are safe in operation.