Infiltration process in the typical soils in the upper and middle reaches of the Yangtze River where is suffering from severe soil erosion are systemically studied based on field experiments in 37 counties with double -ring method.Results show that the fitting precisions with Jiang Ding -sheng formula and Horton Equation are much higher than that with Philip and Kostiakov Equation.Steady -state infiltration rate decrea - ses with increased soil bulk density

but increases with increased total porosity

water stable aggregates

soil humus

and the ratio of silt to clay.Infiltration rates change significantly with soil type due to different soil characteristics.Steady - state infiltration rate varies regularly in different regions.This implies that changes in steady - state infiltration rates in Sichuan basin and Bijie region are the most rapid; in South Shaanxi

South Gansu

and the Danjiangkou Reservoir area

secondary; and in the lower reaches of Jinsha River and the red soil hilly region of South Jiangxi and East Hu.nan

the lowest.The regional differentiation matches with the major sediment source areas in the middle and upper reaches of the Yangtze River.