Abstract: In this paper, it is analyzed that the stress distribution and change of the spiral case of the No.19 hydraulic turbine set in right powerhouse during the different conditions (the press mantling, the constant temperature and pressure, the press dismantling, the electricity generation), and the change rule of the spiral case is studied in the whole process. The stress change is allowed in the design. To one measuring point as an example, using it＇s monitoring data, regressive model to forecast the stress of the spiral case under the normal water level is set up.