Vegetative growing patterns are important factors in soil erosion modeling. Vegetation growth is limited mainly by precipitation. Field measurements of three years were analyzed to study on the influence of interannual and seasonal change of precipitation on the coverage and height of six types of vegetation. The following results are derived: ①Silver chain, shrub, waste-land vegetation and crop of the six types under research are influenced remarkably by annual precipitation with the peak coverage in draught year is only half of that in medium precipitation year. As for vegetation height, fallow-land vegetation and crop are most influenced by annual precipitation. ②The distribution of precipitation in a year, especially the total rainfall from June to August, is a crucial factor for vegetation coverage and height. Present data show that it influences waste-land and cropland very obviously. And Crop canopy and height are determined by the total rainfall in the growth season. The results of this study are useful reference to estimating of vegetation parameters on the Loess Plateau and further to soil erosion modeling and the project of returning cropland to forest and grass.