The water inlet channel is an essential component of the thermal power plant’s circulating water system. It primarily arranges the water flow in the channel so that it is introduced into the pump room smoothly, steadily, and uniformly. Significantly, the operation state of the circulating water pump is impacted by the flow condition of the water inlet channel. The coal-fired generating set’s water input channel was chosen as the research object in this work, and the Computational Fluid Dynamics (CFD) Method was used to examine hydraulic issues impacting anomalous vibration of circulating pumps. Nine optimization options were also suggested, and the effects of the various plans on the water inlet channel’s flow state were examined—the simulation’s outcomes. The simulation’s findings indicate that the arc deflector can enhance the water entry channel’s flow pattern. The wall-attached bias flow of the suction chamber vanished, and the constant flow state is present around the pump’s bellmouth. The thermal power unit’s circulating water pump’s vibration was eliminated, and the circulating pump’s operating efficiency increased due to the curved deflector’s rectification procedures being implemented in the forebay. The study’s findings can guide the hydraulic performance optimization of channels for water inlets with similar sideways or high slopes.