基于统计光学理论，建立了适用于同步辐射软X射线的部分相干光的传播模型。利用互强度描述部分相干光，并采取分割波前叠加的方法，引入合理的近似，可以定量分析部分相干光传播一定距离后相干性能的变化。利用该模型分析了传播距离、光源相干长度、光源尺寸等因素对相干性能的影响。另外在上海光源软X射线干涉光刻分支线站BL08U1B进行了相干衍射实验，并利用该模型对实验结果进行了模拟。模拟结果表明，该模型能够准确地模拟BL08U1B的相干衍射图样，计算结果和实验数据符合较好，为设计同步辐射高相干性光束线站提供了理论依据和参考。

A model for partially coherent light propagation suitable for synchrotron soft X-ray is established based on statistical optics theories. We use mutual optics intensity to describe the partially coherent light, and sum the discrete wavefront considering reasonable approximation. The coherent properties after propagating a distance are numerically analyzed with the model. The influences of propagation distance, coherent length of source and source size on the coherent properties at sample position are studied with the established model. Meanwhile, coherent diffraction experiments are carried out in the soft X-ray interference lithography branch beamline (BL08U1B). Simulations on the experimental results are performed according to the model. The results show that the simulations coincide with the experimental patterns. The model can be used for the design of the synchrotron beamlines with high coherent properties.