Through rainfall simulating in laboratory, and observation on soil sample slices, this study intended to disclose crust development, and reveal the relationship between crust and splash erosion. Two kinds of crust, i.e., structural crust and depositional crust, were observed in the experiment. With the development of crust, bigger aggregates and grains were dispersed, and bigger pores formed beneath the crust. The development of crust was also the process of soil resisting splash erosion enhanced.