Abstract: Take 100 kg dry matter for account, during the process of transformation from rice straw to mushroom pleurotus Sajor-caju, 17.56-26.01% of dry matter has transformed into fruitbody, 40.17 -55.08% remained in Mushroom-cultivated medium (MCM); and 18.91-42.27% converted into heat energy or gas. Thus the pre-fermentation stage of substrate in MCM has completed hasically. During the first 20 days of biogas fermentation in the digester, the treatment of MCM may generate faster and producing much more biogas than that of rice straw. 1M3 of fermentation liquid MCM may produce 0.25 M3 biogas/day. Applying of residue of biogas fermentation substrate made the same year rice yield increased 20% in comparison with that of rice straw applied back into soil directly. The continuous application for three years has demonstrated that there are no significant differences between the fertilities of biogas fermentation residue and rice straw.