根据在降雨条件下黄土坡面溶质随径流流失特性，将黄土坡面溶质随径流流失过程看成一个随机过程，应用概率统计学原理，导出了黄土坡面溶质随径流流失的相应函数模型，并利用实测资料推出了模型中的各参数及各参数与其影响因素间的关系，得到了Ｃａ２＋径流浓度相应函数模型，并利用实测资料对模型进行检验，同时对模型存在的问题进行了讨论． According to the characteristics of runoff loss on the loess slope with rainfall, the solute flux on the loess slope surface is treated as a random process with the runoff loss. By using the principle of probability and statistics, the corresponding function model of solute loss with runoff on the loess slope is derived The relationship between each parameter in the model and its influential factors was deduced by using the measured data. Corresponding function model of Ca2 + concentration was obtained. The model was verified by the measured data, and the existing problems of the model were discussed.