In thermally stratified reservoir, a multi-level intake structure is usually adopted in hydropower station to reduce the negative effect of releasing lower-temperature water to the environment in downstream reach. And a simple and practical formula of water temperature released is need. In this paper, based on Nuozhadu Hydropower Station, a model test is conducted to model the thermal stratification of this reservoir, and measure the temperature of water released from the intake structure. A prediction formula of water temperature released is put forward based on the experimental data. The formula is validated by the experimental results of water temperature released from the intakes of Jinping No.1 Hydropower Station.