In order to study the influence of litter to surface erosion,splash amount and plot wash-ing amount were measured respectively on the surface under middle-age Mountain Poplar forest.There are two surface conditions,the first one,litter was cleared off,and another one,the initiallitter(2 cm deepth)still stayed on the ground.The results showed there are not splash erosion onthe surface on which there are initial litter and there are micro splash erosion on the surface onwhich litter had cleared off. The runoff amount were increased by 8.72%from0.257 4m³/(100m²·a)to 0.282 0m³/(100m²·a).The erosion modalus were increased by 56.08%from 1.591 5t/(km²·a)to3.623 5t/(km²·a).Because of good protection of inital litter,surface erosion hardlyoccur in the catchment area of Mountain Poplar forest.