Complex fracture technology is one of the keys to the successful development of unconventional oil and gas reservoirs such as shale. At present, most studies focus on how to improve the complexity of fracture network. It is still unclear whether proppant can enter branch fractures at all levels after the complex fractures are formed. Numerical simulation and indoor experiments provide some qualitative results, but there are still lack of quantitative models. Thus, the liquid distribution model and the proppant turning law are proposed in this paper to predict the proppant transportation behavior in the complex fractures. The results show that the prediction accuracy of this model is higher than that of previous ones. In addition, the influence of branch fracture angle on the liquid distribution is discussed. Finally, an engineering case is studied with this model, and some suggestions are provided for the fracturing parameter optimization.