Abstract: In order to study the effects of different inorganic elements to biodegradation strains, eight macro elements and trace elements were analyzed by univariate and multivariate analysis in shake flask, thus the optimum nutritional conditions that two biodegradation strains degraded wheat-straw were determined, and then the degradation effects during different pH and time were discussed. Results indicated that, the optimum inorganic nutritional condition and dosage of DG75B strain were Ca 0.005%, Mg 0.015%, Mn 0.0005%, Fe 0.0005% , Mo 0.0005% , on this condition, wheat-straw weightlessness rate was 40.59% after 5 days’treatment, increased by 10.29% in comparison with the control. And the optimum pH to straw degradation was about 6-7. The optimum nutritional condition and dosage of LYZ22 strain were Ca 0.01%, Mg 0.03%, and the optimum pH was about 6. During forty days, variation trend of wheat-straw weightlessness rates and different component contents were from slow to fast in flask, straw weightlessness rate was 43.19% , increased by 16.07% compared to T_strain. The contents of straw cellulose, hemicellulose, lignin decreased by 43.18% , 54.77%, 22.96%, in comparison with T_strain the rates increased by 17.29%, 15.36%, 11.28% respectively. Trend of wheat-straw weightlessness rates and different component contents were from fast to slow in experiment of straw returning in sixty days; straw weightlessness rate was 48.48%, increased by 21.88% compared to T_strain. The contents of straw cellulose, hemicellulose, lignin decreased by 48.27% , 51.41% , 13.83% , the rates respectively increased by 17.95%, 26.52%, 15.81% in comparison with T_strain.