Forest l itter is the physical makeu p part of forest ecosystem．The rate o f decompositi on of forest litter is low in temperate and cool temperate zones．There is impor tant signific ance to search and utilize the functi on of soil animals，in order to probe the material circulation and energy flow in forest ecosystem．We selec ted three kin ds of mesh bag with different mesh size，in which，large pore mesh bag is large enough to permit the activities of all kinds of soil animals，medi um mesh bag is designed to exclude the function of soil macrofauna，while small mesh bag is small enough to exclude the effects o f any kind of soil animals as far as possible．The decomposition time is thr ee years．The studying results sh ow that：the decomposing speed of the bags with big meshes，under functions of a ll kinds of soil animals，faster than the bags with medium meshes，under functio ns of medium and small soil animals，as well as the bags with small meshes that exc luding all possibility of functions of soil animals；in the process of dec o mposition of litter，relationship of the litte r lost weight with number of soil anim als is not obvious clearly；the degre e of functions of soil animals to so ft litter higher than hard litter；according to the an alysis of diversity index ，no regula r changes will happen to the diversity of soil anima ls as the time of decomposing samples lengthen． Forest l itter is the physical makeu p part of forest ecosystem. The rate o f decompositi on of forest litter is low in temperate and cool temperate zones. There is impor tant signific ance to search and utilize the functi on of soil animals, in order to probe the material circulation and energy flow in forest ecosystem. We selec ted three kin ds of mesh bag with different mesh size, in which, large pore mesh bag is large enough to permit the activities of all kinds of soil animals, medi um mesh bag is designed to exclude the function of soil macrofauna, while small mesh bag is small enough to exclude the effects of any kind of soil animals as far as possible. The decomposition time is thr ee years. The studying results sh ow that: the decomposing speed of the bags with big meshes, under functions of a ll kinds of soil animals, faster than the bags with medium meshes, under functio ns of medium and small soil animals, as well as the bags with small meshes that exc luding all possibility of functions of soil animals; in the process of dec o mposition of litter, relationship of the litte r lost weight with number of soil anim als is not obvious clearly; the degre e of functions of soil animals to so ft litter higher than hard litter; according to the an alysis of diversity index, no regula r changes will happen to the diversity of soil anima ls as the time of decomposing samples lengthen.