As a watershed important water transfer project, the influence of Water Diversion from Yangtze River to Lake Taihu Project(WDYT) on the lake current of Gonghu Bay has always received a substantial amount of attention. During the summer of 2022 (August 25-September 5) and the winter of 2023 (January 18-February 28), nine sites were set up in Gonghu Bay to conduct a study on the movement characteristics of the lake current under the combined influence of WDYT and the wind field. It was proposed that chloride ions could serve as natural tracers to observe and simulate the movement characteristics of the Yangtze River water entering Gonghu Bay, and a numerical model was established. The reliability of the model was verified based on tracer particles. Both in summer and winter, the vertical average current velocity in Gonghu Bay showed high values in the estuarine area and boundary section, but low values in the intermediate transition zone. Current velocity in the estuary area was primarily influenced by WDYT, while current velocity in the intermediate transition area and boundary section was mainly affected by the wind field. The vertical mean current field of Gonghu Bay could be divided into four types: clockwise, anticlockwise, two sides in, middle out and two sides out, middle in. To some extent, WDYT will speed up the current rate of some areas of Gonghu Bay, and the diversion of water has an obvious effect on the improvement of current velocity at the central axis of Gonghu Bay.