This paper reviews representative slope steepness classification of FAO,Australia ,International Geographical Union Geomorphological Survey and Maping Council and Japanj small watershed slope map of 1950's yellow River soil and Water conservation survey team, and Zhu Xianmo's, Tang Keli,'s slope classification for soil erosion, and so on.We take the Wangdong watershed experiment area as an example of plateau area of leoss plateau, study the contribution of slope and discuss the classification, then, divided slope into 3 groups and 9 classes.