Surface water-heat-carbon fluxes are critical indicators reflecting the water-carbon cycles in lake ecosystems under changing climates, yet the impact of extreme environmental conditions such as drought on these processes remains to be further clarified. Poyang Lake is the largest freshwater lake in China and an internationally important wetland. It is not only a key node for the regulation of water resources in the Yangtze River Basin, but also plays an important role in the global carbon cycle and water cycle. In 2022, a rare consecutive meteorological drought event occurred in the Poyang Lake Basin during the summer and autumn seasons, and the most severe drought since 1949 hit the lake area. In this study, the multi-year monitoring data from the eddy covariance instrument at the Poyang Lake Wetland Observation and Research Station were adopted. The station is located on the beach of Poyang Lake (29°27" N, 116°03" E), and it has been continuously monitoring the variation processes of the water-heat-carbon fluxes in the lake since 2015. This study analyzed the variation patterns of water-heat-carbon fluxes and their response characteristics to the extreme drought event in Poyang Lake, in 2022. The results showed that: (1) On an annual scale, the latent heat flux was relatively high from July to September, with the peak value occurring in August, and the annual average value was 49.5 W/m2. The sensible heat flux was relatively high from September to November, with the peak value occurring in October, and the annual average value was 10.6 W/m2. The CO? flux exhibited obvious seasonal variations, and the carbon source and carbon sink shifted with hydrometeorological factors such as water level and net radiation. The annual CO? flux average value was 15.0 μmol·m?2·s?1. (2) On a daily scale, the sensible heat and latent heat fluxes were basically synchronous, showing a single peak at noon, while the CO? flux had a single peak at night. (3) The extreme drought event significantly intensified the carbon source effect of the wetland ecosystem by changing the energy allocation pattern. During the drought period, the latent heat flux, sensible heat flux, and CO? flux increased to 1.23 times, 1.78 times, and 5.44 times of the average values in the same historical period, respectively. (4) The correlation analysis showed that air temperature, wind speed, net radiation, precipitation, relative humidity, NDVI, and water level were the main factors affecting the water-heat-carbon fluxes. The stepwise regression analysis further revealed the influence mechanisms of various factors on the fluxes under different periods and underlying surface conditions. During the extreme drought period, when the underlying surface was water body, the importance ranking of the influencing factors for the latent heat flux, sensible heat flux, and CO? flux was: wind speed, air temperature > relative humidity > net radiation, water level. When the underlying surface was the beach, the importance ranking of the influencing factors for the latent heat flux, sensible heat flux, and CO? flux was: air temperature > wind speed, wind speed > NDVI, air temperature > VPD > precipitation. The extreme drought event mainly promoted the energy allocation to the sensible heat flux through the increase of air temperature, wind speed, and net radiation, and significantly stimulated the CO? release. This study revealed the response mechanisms of water-heat-carbon fluxes in lakes to extreme climate events and provided a scientific basis for predicting the responses of lake ecosystems under future climate change scenarios.