After impoundment of the Three Gorges Reservoir, the tidal characteristics of the Yangtze River Estuary could be changed. Based on the measured tidal level data of 6 representative years at the 6 tidal stations distributed in the Yangtze River Estuary, the tidal characteristics of the Yangtze River Estuary were compared and analyzed by using the tidal harmonic analysis method. The results show that, after impoundment of the Three Gorges Reservoir, the harmonic constants of the main tidal and tidal characteristic parameters in the Yangtze River Estuary changed, but the range of change is relatively small.