通过对几种确定背压变化对汽轮机热经济性影响计算方法的分析，指出各方法存在的问题，并重点对常用的热力学方法存在的问题进行了分析，指出基于详细计算的方法能进一步提高计算精度，并以２００ＭＷ汽轮机为例，对基于热力学方法和基于详细计算方法得到的背压变化对热耗率的修正曲线进行了对比。 By analyzing several calculation methods to determine the influence of back pressure on the thermal economy of steam turbines, the problems existing in each method are pointed out. The problems existing in the commonly used thermodynamic methods are also analyzed. It is pointed out that the method based on detailed calculation can further improve the calculation Taking the 200MW steam turbine as an example, the correction curve of the heat rate is compared with the change of the back pressure based on the thermodynamic method and the detailed calculation method.