Abstract: Selective withdrawal measures are an effective means to alleviate low-temperature water discharge in reservoirs. Clarifying the transmission and hysteresis laws of selective withdrawal measures along the upstream reservoir to the downstream reservoir of cascade reservoirs is of great significance for building a joint water temperature regulation system. A two-dimensional hydrodynamic water temperature mathematical model of the Wudongde Reservoir was employed using the CE-QUAL-W2 model in this study, and based on the 2022 scheduling process, two scenarios of single-layer water intake and designed stoplog gate operation were set up. The impact of stoplog gate on the water temperature rhythm of Wudongde Reservoir and its downstream attenuation characteristics were quantitatively analyzed. The research results indicate that the operation of the stoplog gate could significantly improve the position of the flow layer, causing the average water intake elevation to rise from 935.1 m to 952.2 m, promoting the mixing of surface water bodies, and resulting in a maximum reduction of 2.3 ℃ in vertical temperature difference compared to single-layer conditions under design conditions. Under design conditions, the discharge water temperature is increased by an average of 0.5 ℃ compared to single-layer water intake, with an average improvement of 0.1-1.0 ℃ over ten days. Due to the influence of downstream cascade regulation and storage, the effect of stoplog gate in Wudongde Reservoir has significantly declined along the way, with an average improvement range from 0.49 ℃ to 0.16 ℃, and a maximum improvement effect decrease of 1.01 ℃. The effective manifestation time of Baihetan Reservoir, Xiluodu Reservoir, and Xiangjiaba Reservoir lags behind by 16 days, 53 days, and 62 days, respectively. The research results can provide scientific basis for optimizing the layered water intake scheduling strategy of cascade reservoirs and ensuring the ecological water safety of the basin.