In order to find the new way to promote the degradation rates of crop straws, the influences of outer cellulose on degradation rates of straws and available nutrients of soil were investigated by incubation experiments. When the incubation finished, the degradation rate of wheat straw added cellulose were increased 7.10% -11.86%, and the rate of corn straw were increased 8.01% ~ 14.04%. Compared with the CK, the contents of soil available N, available P and available K for the optimal Tr of wheat straw were increased 4.15, 3.60, 32.35 mg/kg, and for the Tr of corn straw were increased 6.50, 4.27, 47.97 mg/kg respectively when the incubation finished.