Abstract: Results from field experiments showed that by rice straw mulch, contents of soil N,P,especially organic matter and available K are increased,and soil physical structure was improved with soil porosty inreased and soil volumetric weight reduced. Straw mulch has also the functions in reducing soil evaporation, regulating soil temperature and decreasing soil weed density. Thus the wheat yield was increased 13.5 to 46.1%,that is per Kg rice straw increasing wheat yield at 0.12 to 0.23 Kg.The optimal rice straw mulch quantity was 3000kg/hm².