The knowledge about characteristics and erosion effect of the development of soil crust is very important to exploration of soil erosion mechanism and construction of accurate prediction model for soil erosion Through experiments of events of simulated rainfall, development process of soil crust with or without raindrop impact and dynamic soil erosion effect of crusting in the initial period with or without soil crust on loess was discussed Results show that (1) with rainfall going on, bulk density and shear strength (with moisture content at 20%) of the crust genetic horizon increased steadily; a stable crust, 3～4 mm thick, formed within 30 min; (2) soil crust development process remained more or less the same with or without raindrop impact, except for variation in degree, and the contribution of raindrop impact to crust formation was basically similar to that of soil humidification; (3) shear strength of the soil surface varied sharply between with crust and without crust at the initial period of rainfall, and the difference narrowed rapidly and tended to merge Therefore, the effect of crust development on anti-erodibility was very weak. Variation of cumulative splash erosion was attributed to variation of the starting time of splash erosion; (4) the existence of soil crust on loess significantly decreased infiltration but increased runoff. But the effect of crust disappeared gradually with rainfall going on The function of splash erosion is expressed as C = 0.667 0 ln(t) -3.245 9, which, coupled with the splash erosion model (S_c= S_uc /(1-C)), can be used to accurately predict the cumulative splash erosion within a certain period during the rainfall in loess without crust.