[Objective] The preferential flow morphology and characteristics of red soil in the arid and hot valley of the Honghe River was studied, in order to provide theoretical basis for regional water resources management and soil erosion prevention. [Methods] Taking typical vegetation—woodlands and wild grasslands in arid and hot valley regions as the research objects, the morphological distribution characteristics of preferential flow and its response to the characteristics of read soil were studied by using field dye tracing method and image processing technology. [Results] ① The average stained area of forest and grassland was 87.2% and 91.97% respectively. The stained area decreased with the increase of soil layer, and rebounded in local depths. The preferential flow length index of forest and grassland was 766.8% and 730.0% respectively. And the priority flow of the forest was more developed than wasteland. The maximum staining depth of forest and grassland was 40 cm and 35 cm respectively. ② The width of the dyeing path decreases with the increase of the soil layer. In the 0—20 cm soil layer, the main dyeing path was greater than 250 mm. The dyeing path within 20—40 cm was mainly in the layer between 20—250 mm, and the dyeing path was less than 20 mm in the soil layer below 40 cm. ③ There were significant correlations between the priority flow dyeing area, length index, dyeing path width and soil factors. The cumulative contribution rate of total porosity, organic matter, and moisture content to dyeing area ratio (D_A), length index (LI) and dyeing path width (SPW) was 97.8%, 86.95%, 87.45%, respectively. The factors such as moisture content, organic matter, bulk density, total porosity and Al³⁺ had the best linear relationship with dyeing area and dyeing path. [Conclusion] The combined effects of soil pore characteristics, base ions, and soil texture ultimately led to the difference in preferential flow between forest and grassland in the arid and hot valley of the Honghe River.