Vegetation is one of the important factors affecting soil and water loss,thus is regarded as one of the key parameters of soil erosion prediction.It's well known that the vertical structure of vegetation is composed of different layers and each layer has different impact on soil erosion,yet the traditional coverage cannot reflect the impact of different layers on soil erosion,and sometimes overestimate or underestimate the impact of vegetation on soil erosion.With the consideration of this fact,a new vegetation factor index Cs,structured vegetation factor index,was proposed and the vegetation index factor models have been established using multiple regressions in this paper.The case study in the locust tree and the Chinese pine communities showed that tree layer,herb layer and litter layer are important to prevent the soil erosion and their weights are 0.0150,0.591,0.394 and 0.0608,0.828,0.112 respectively for the Chinese pine and the aspen communities.Structured vegetation factor index,which considering the relative roles and coverage of each layer in the vegetation communities,could be better than traditional coverage in describing the relationship between vegetation and soil erosion.This could be an idealized indicator and have great significance for both soil erosion evaluation and prediction and the vegetation constructions for soil and water conservation.