Abstract: Aiming at studying the mechanism of curtain weirs and controlling algal blooms of Xiangxi Bay in the Three Gorges Reservoir, based on the field data collected from January to December 2010 in Xiangxi Bay, this study analyzed the temporal and spatial variations of water temperature with and without curtain weirs by using CEQUALW2, a laterally averaged two dimensional hydrodynamic and water quality model. The results showed that the performance of curtain weirs was varied for different heights, different locations and different seasons. The curtain weir can change the water temperature of its upstream, especially the surface water temperature, the greater the height of the curtain weir was, the more the days when water temperature decreased would be, moreover, the greater the average daily water temperature difference would be, the influence of curtain weirs on water temperature was more obvious in summer and autumn, and reduction of water temperature was in the same period; the performance was more obvious as the curtain weir was installed further downstream and the height of it was greater, and in autumn, the change of water temperature in different layers compared with the scenario without curtain weirs was greater, especially in the layers close to the water surface; the curtain weir can change the flow, on one hand, the upstream inflow would flow down and mix with water in lower layers around the curtain weir, on the other hand, the intrusion flow from the Three Gorges Reservoir would be changed and mix with water in lower layers or shallower layers around the curtain weir, meanwhile, the curtain weir would promote vertical mixing, then make the water temperature in certain water areas tend to be uniform, finally weaken the water temperature stratification. CEQUALW2 model was suitable for the simulation of curtain weirs in Xiangxi Bay, and the study of curtain weirs would provide technical support for algae control in the tributaries of the Three Gorges Reservoir.