To investigate the contribution and temporal variability of lake-groundwater interactions in the water balance of flood-controlled lakes, Honghu Lake in the middle reaches of the Yangtze River was selected as a case study. Based on the analysis of water level dynamics of Honghu Lake and surrounding groundwater, the recharge-discharge relationship between Honghu Lake and groundwater were identified and calculated by a water balance equation. The contribution of groundwater-lake interactions to the water balance of Honghu Lake and its temporal variability were examined. The results indicate that there is a significant water level difference between Honghu Lake and the adjacent phreatic groundwater, with dynamic changes in both showing a significant positive correlation, correlation coefficient r = 0.729. The aquifer in the Honghu Lake area is permeable, which indicates that there are interaction conditions between Honghu Lake and groundwater. On an inter-annual scale from 2017 to 2022, Honghu Lake generally infiltrate into the groundwater, with an average annual discharge volume of 6.43 × 10⁸ m³, accounting for 14.11% of the lake's outflow. On a multi-year average monthly scale from 2017 to 2022, Honghu Lake infiltrates into the groundwater during the dry season (September to February of the following year), with an average monthly discharge volume of 0.8 × 10⁸ m³. During the rainy season (April to August), groundwater-lake interactions are dynamic, with an average monthly exchange volume of -1.17 × 10⁸ ~ 0.88 × 10⁸ m³. Honghu Lake presents an opposite seasonal variation characteristic of the lake water-groundwater interaction compared with the reported Yangtze-connected lakes such as Poyang Lake and Dongting Lake. This is mainly because the water level of Honghu Lake, affected by water conservancy regulation, has altered the natural interaction process between the lake and groundwater. These findings provide new insights into groundwater-lake interactions in flood-controlled lake systems and hold significance for the management of water resources and ecological protection in the Honghu Lake region.