The thermal stratification structure of a reservoir or a lake is important to its dynamics and environmental process. Although many scholars have studied this topic, a gap is still existed on the process of heat exchange in the air-water interface and the contribution mechanism of various meteorological factors. In this paper, based on the observation data of water temperature and meteorology from March 2019 to February 2020, in Xiangxi Bay of the Three Gorges Reservoir, we studied how the heat flux and wind stress affect the vertical structure of water temperature and the turbulent mixing. We have conclusions as following. (1) The Xiangxi River is characterized as stratification in high temperature period and mixing in low temperature period. The depth of mixing layers in high temperature period is less than 8 m and that in low temperature period is more than 30 m. (2) Solar short-wave radiation is the main heat source of Xiangxi Bay, while latent heat flux and long wave radiation are the main cold source. The contribution of sensible heat flux is quite small. (3) The wind speed in Xiangxi River region is weak, with an average value about 1.6 m/s, which influence the water vertical stability by enhancing latent heat and sensible heat flux strongly and mechanical disturbance effect weakly. (4) The turbulent energy flux of surface water is much lower in the high-temperature period (10^-7 m³/s³ in magnitude), at which time the wind stress dominates the development of turbulence. The turbulent energy flux is quite high during low-temperature period (10^-6 m³/s³ in magnitude), when the sensible heat flux and long wave radiation dominate the turbulence mixing.