The spatial distributed characteristics of soil erosion on straight hillslopes before and after erosive rainfall are studied with ⁷Be trace method and field investigation. The results showed that within 20 m of slope length,⁷Be inventory at 0～2 cm deepth of soil profile in different sloping locations was not significant before occurrence of erosive rainfall,but after occurrence of erosive rainfall in 2004, ⁷Be inventory in different sloping locations was great significant.⁷Be inventory at 0～2 cm deep after occurrence of erosive rainfall and difference values of ⁷Be inventory before and after erosive rainfall occurrence decreased as slope length increased with 20m slope length. This indicated that soil erosion increased generally as the increase of slope length. There are great differences in detachmentor deposition process at different sloping locations. At 0～5 m slope length of the upper slope,deposition process was dominant; but at 8～15 m of slope length, detachment was dominant, where soil erosion was very severe.