A strain named of CKB that can efficiently degrade straw was selected from soil where growing rice perennially and which was identified as Aspergillus niger by ITS sequence analysis. In the normal soil temperature and environment, the straw was degraded by the bacteria for 35 days, and the weight loss rate reached 49%. Furthermore, the degradability of cellulose and lignin by CKB was also investigated. At 72 h of the degradation, the converted glucose concentration from cellulose was 0.554 g/L, while the amount of lignin degradation was 0.607 g/L. The effect of substrate concentration, pH, and temperature on the degradation of cellulose and lignin was investigated. The structural change of straw before and after degradation were observed by SEM. The products of degradation were detected and characterized by means of Pyrolysis⁃GC/MS; the degradation mechanism of Aspergillus niger CKB was explained.