Abstract: The experiment simulated the erosion development process of slopes under natural conditions through multiple precipitation intervals on the slope surface,which fully represented the process from rill to shallow rill. Three-dimensional scanning data of slope erosion gully morphology at different erosion stages were obtained by sectional observation of slope erosion process. According to the change of width and depth of gully at different erosion stages on slope,the development process of gully on slope from rill to shallow gully was studied. The results showed that at the beginning of rainfall,the width of erosion gully was obviously more than the depth,and the cross-section of erosion gully at the beginning was shallow and wide. With the increase in rainfall duration,the average depth of erosion ditch increased rapidly. At the end of the test,the average depth and average depth growth rate of the erosion ditch were more than the average width. During the development of trench to shallow trench,trench with width exceeding the upper limit of trench（20 cm）first appeared,and its proportion increased with the increase in rainfall duration. Shallow ditches with a depth more than 20 cm appeared later than those with a width more than 20 cm. The erosion rate of gully wall was relatively stable during the development of gully. As the soil bulk density increased with the increase in soil depth,the cutting erosion under the ditch slowed down with the increase in ditch depth. This led to the transition period channel in which the width exceeded the upper limit of the rill and the depth does not reach the lower limit of the shallow ditch depth. With the development of erosion process,the number and frequency of ditches in the transition period increased gradually. As the runoff was mainly concentrated in a few erosion ditches,the vast majority of rills would not develop into shallow ditches. These rills were either swallowed or maintained in the slow rill development stage for a long time. In the process of erosion,only a few rills could eventually develop into shallow gullies,and the maximum proportion of shallow gullies was only 2.3%. After the emergence of shallow ditches on the slope,the width and depth of erosion ditches with ditch depth less than 20 cm in the section of erosion ditches on the upper,middle and lower slopes of the slope still changed obviously. The development of erosion ditches mainly focused on the deepening and widening of the original erosion ditches. After the emergence of shallow ditches,the runoff on the slope was more concentrated in the shallow ditches,and more erosion was concentrated in the side wall erosion and undercut erosion of the shallow ditches. At the same time,rill erosion in other parts of the slope was weakened,resulting in the decline of the overall erosion speed and sediment yield of the slope.