Based on abundant experimental data and traditional method of calculating the benefits of runoff and sediment reducing by soil and water conservation sloping measures,this paper obtains the flood reducing amount of different measures on experimental plots through constrasting the flood discharge of controlling area with uncontrolling area in same flood frequence,and popularize this results to whole watershed .We get the flood reducing amount under different measures in watershed ,and then use the flood～sediment relationship to calculate the sediment reducing amount by flood reducing amount in whole watershed,we get an avilable method to calculate the benefits of runoff and sediment reducing by different measures.