Abstract:A complex microbial system(CMS) WSS-1 was screened and domesticated from the soils which had a long term straw-returning to fields in Sichuan Province using the restricted cultivation and gradient-temperature induction methods. The WSS-1 could completely decompose filter paper within 4d at 28℃ implying that it had the potential of degrading wheat straw under natural condition. The peak of cellulase production by WSS-1 appeared in the sixth day of the wheat straw decomposition experiments, four days earlier than that treated with the widely used Inoculant A. The tension value at breakpoint of wheat straws treated by WSS-1 could decrease by 73.66% after 20d, which was about 33.7% and 8.9% less than that of the control and the Inoculant A treatment, respectively. The bacterial composition of WSS-1 was analyzed by using 16S rDNA clone library method. The dominant communities of WSS-1 were Bacillus subtilis, Bacillus sphaericus, Alcaligenes faecalis,Clostridium bifermentans and Enterococcus faecium.