Abstract: Loess plateau is one of the most serious regions of soil erosion in China，and it also is main source of sediment of Yellow river.In recent decades，China made great achievements in dam flood insurance harvest technique and engineering design.It played a good role in guiding for construction of silt dam.With the level of economic development constantly improving，reasonable evaluation of dam system planning is also put forward higher requirements.Reasonable planning and evaluation method of small watershed dam system in the west of Shanxi province and even the whole loess plateau were put forward.It provided an important decision basis to promote dam system develop healthily in the future.