While the low-pressure water spraying device  is used, the following points shall be used. In order to prevent the cylinder temperature sudden drop, and to avoid too quickly shrinking of exhaust cylinder, in order not to affect the normal expansion difference of low pressure cylinder. The operation practice shows that  due to the steam flow back flowing existing at the flow-path of several stages at end of the steam turbine, the spraying water will be taken at the steam side of the  blade root, which will  have certain erosion effect on the last stage blade. Therefore,  it shall be avoided that water spraying device is used under long-term low load condition. Pay attention to the exhaust cylinder temperature decreasing after water spraying, if the decreasing is not obvious, it  may be caused by insufficiently water spraying pressure, too small flow and spraying hole blockage, so unchoking shall be done as possible.（js）