The benefits of economic and soil and water conservation of yang woodland and grassland are analysised during the comprehensive control of small watershed in loess hilly region in Ansai. The runoff plots were used in observation of sediment reduction, and aboveground biomass of1-5 years yang woodland and grassland were measured in evaluating economic benefit. The species of grasses and trees as well as its structures with high economic benefit and growth rate were advanced for comprehensive control of small watershed in this region.