A method for determining the optimal amount of litter on woodland is developed according to theory of optimization on the premise of giving integrated consideration to soil water,soil erosion and soil temperature regimals. The optimal amount of litter determined by this mathematic model for larch (Larix pricipis-rupprechtii Mayr) and oak (Quercus liaotungensis Koidz) stands is 16.0 tons/ha and 10.5 tons/ha respectively.The model can be used in any site by changing parameters in the model.