Taking the typical slope of the Chongling Basin in the Taihang Mountain area as the research object, the dye tracer experiments with Blue-FCF and KI were performed. The image processing software was used to explore the changes of preferential flow morphological characteristics at the five different slope positions. The results showed that:(1) With the increase of altitude, the soil thickness and bulk density of each slope position gradually decreased, and the total porosity, permeability coefficient and saturated moisture content gradually increased, while the wilting coefficient and field water holding capacity tended to fluctuate. (2) With the rise of slope position, the depth of dye migration increased, the matrix area decreased and the preferential flow area gradually increased; the stained area rate of dye infiltrate decreased with the increase of the depth. The interaction between soil moisture and surrounding soil in the depth below 40cm was weaker than that in the lower slope; the volume of dye infiltration increased gradually as the rise of slope position; (3)As the slope position increased, the contribution of the preferential flow to the actual water transport increased and the water flow infiltrated with preferential flow as the main method on higher slope; (4) Soil texture and bulk density were the driving forces for the difference of preferential flow at different slope positions in earth-rock mountainous area.