Through analysis of soil particles situation in 4 different forestlands of Quercus aliena,Lithocarpus fangii,Cryptomeria fortunei and Phyllostachys heterocycla cv.pubescens in Simian mountains in Chongqing,the relationship between different forestland soil particles characteristics and soil erosion was discussed.The results showed that most of the forestlands soil were good gradation soil except Cryptomeria fortunei.Phyllostachys heterocycla cv.pubescens forestland.Surface soil particles dispersion was lowe...