The benefits of soil and water conservation mainly include the economic, social and ecological benefits and the benefits of reducing flood and sediment. Reducing of flood and sediment is the basis of other benefits and economical benefit is the aim of other benefits. The important economical benefits include the increasement of agriculture production by holding of water and soil, and social and ecological benefits by reducing of flout and sediment in protection of people's lives and properties and economical construction of water conservancy transportation, industry, mining, cities, countryside and so on.Appropriate analysing and calculating methods for all kinds of benefits are introducd. The benefit of reducing flood and sediment is mainly calculated by conservation and hydrological method in comparision paying attention to the affection of new loss of soil and water and other facts. The benefits related to agriculture, forestry, animal-husbandry and some else should be differentiated in analysing and calculation, the related data of all kinds of benefits in order to determine their proper nature and exact quantity.