Abstract: The soil animal community and its fluctuation during leaf litter decomposition was investigated with litterbag(5 mm,1 mm and 1/300 mm)method(from Apri.to Oct.,2002) in oakery(Quercus liaotungensis)forest and in mixed forest(oakery∶pine(Pinus tabulaeformis)= 2∶1)at Jiulongshan,Beijing.3 564 individuals were collected from 98 litterbags,belonging to 3 Phyla,10 Classes,19 Orders.Most of the dominant taxa were Hymenoptera,Psocoptera,Diptera,Collembola and Acariformes.Most were omnivores in the forest litter.The number of individual and group of meso-and microfauna in mixed forest were more than that in the oakery,while the macrofauna were less than that in the oakery,the number of individual and group were not significant at α=0.05 to two type forests.In the three kind of litterbags,the amount of the soil animal individual and group were in the order of 5 mm>1 mm>1/300 mm in pure oakery forest,while the amount of soil animal individual was 1 mm>5 mm>1/300 mm,and the group was 5 mm>1 mm>1/300 mm in mixed forest,and the amount of group reached the peak at Aug.or Sept.The diversity of the soil animal group was trending to increase;Soil animal community was more heterogeneous in different forest.The dominant taxa showed that they were not significant in correlated to the mass loss of the litter(r_s 0.05).The colonized duration of Acariformes and Psocoptera were 10.33 and 8.53 months at oakery,respectively,while that of Hymenoptera and Diptera were 9.48 and 7.91 months respectively in mixed forest.