The preferential flow, a term proposed by scholars according to water transport in soil in recent years, is the symbol of soil water transport mechanism study transforming from uniformity to non-uniformity. It can be defined as the unstable seepage phenomena of water and solute along the specific path, under the impacts of multiple factors. It is one of main causes that lead to geological hazards of rainfall-induced landslides, debris flow, and groundwater pollution, nutrient loss in farm field, so the study on preferential flow is particularly important. This paper, beginning with the definition of preferential flow, mainly reviewed the study development on mathematical models and technical means, and at the end the existing problems were discussed and the future research was put forward.