Abstract: Phanerochaete chrysosporium was used to dispose wheat straw under different conditions of biological pretreatments, including water ratio of wheat straw, inoculation quantity, nutrition source and pretreatment time. Through measuring the decomposition rate of cellulose, pentose and lignin, it shows that the optimal conditions of biological pretreatment have been achieved by the combination of 80% water ratio of wheat straw, about 10 days of the duration of biological pretreatment along with the addition of 0.25% of nitrogen source, with the strain growth unaffected by the inoculation quantity.