In order to explore the correlation mechanism between preferential flow and soil mechanics in the gully area of the dry-hot valley of Jinsha River and reveal the characteristics of soil shear strength under the influence of priority flow,to enrich the mechanism of gully erosion in the development area of hot and dry river valleys and provide theoretical basis for further gully erosion control in this area,the intact gully in the typical gully development area were selected as the study object,and based on staining tracer,soil physicochemical and intact soil straight shear experiments,the correlation between priority flow and soil mechanical indexes were analyzed by statistical methods such as RDA,and to clarify the relationship between preferential flow and shear strength.The results showed that:(1) Due to the development of ditch,the preferential flow development degree from the catchment area to the bottom of the ditch was gradually reduced.The soil moisture content,bulk density,total porosity and organic matter content in the preferential flow area were higher than that the matrix flow area,and the fractal dimension of mechanical composition in the matrix flow area (2.680~2.874) was greater than that in the preferential flow area (2.746~2.893).(2) The preferential flow area in the gully area affects the soil cohesion and strength,which will reduce the soil shear strength to a certain extent.The shear strength of the water catchment area and the trench head was greater than that of the ditch bed and the ditch bottom.The cohesive in the preferential flow region (1.24~2.65 kPa) was smaller than that in the matrix flow area region (1.91~4.27 kPa),the internal friction angle in the preferential flow region (19.52°~22.47°) was slightly larger than that in the matrix flow area region (17.68°~22.35°),and the shear strength of the preferential flow area region (36.66~43.68 kPa) was generally smaller than that of the matrix flow area region (38.74~47.32 kPa).(3) The preferential flow had different degree of correlation with soil cohesion and internal friction angle.Soil cohesion was significantly negatively correlated with dyeing area ratio and stroma flow depth,while internal friction angle was negatively correlated with the percentage of the preferential flow and dyeing area ratio of preferred flow area.The shear strength was inversely correlated with the ratio of staining surface,the maximum dyeing depth,the percentage of preferential flow and the dyeing area of the preferential flow area.