[Objective] Summary and review of the research status on the preferential flow-induced sliding effects developed by the existence of dominant channels such as joints, fissures and holes in the slope were conducted, in order to draw the attention of scholars to the application of preferential flow theory in the study of slope geological hazards and provide scientific basis for accurate forecasting and early warning of landslides. [Methods] According to the definition and types of preferential flow, the influential factors of preferential flow were analyzed, and the current status of the influence of preferential flow on slope stability, the preferential flow detection technology and the stability evaluation model of slope were reviewed and evaluated emphatically. The developing process of preferential flow-induced landslide effect on loess slope was summarized as four stages, and the typical landslides were taken as examples. Finally, the issues of the preferential flow-induced sliding mechanism were clarified. [Results] The preferential flow widely developed in the dominant seepage channels of the loess slope is a reasonable explanation for slope instability under the condition of limited rainfall depth. However, the theory and application of preferential flow in landslide hazards prediction still need more practical tests. [Conclusion] Slope preferential flow is an important theory in hillslope hydrology, unsaturated soil mechanics, geo-hazards science and other related disciplines. Many achievements have been made over the years. In the future, it is necessary to further study the effect of preferential flow-induced sliding on loess slopes, and strengthen the application of multidisciplinary and new technologies to improve the level on scientific prediction and prevention of geo-hazards.