Bacillus subtilis C7 has ability to synthesize cellulase and phytase to hydrolyze cellulose and phytase in cassava residue. This research studied factors that were influential in the productivity of cellulose and phytase hydrolysis in cassava residue with Bacillus subtilis C7 to choose suitable factors for fermentation. Research results showed that suitable fermenting time was 48 hours, fermenting temperature was 36oC +/- 1oC, the ratio of water and mixture was 2:1, the content of added soybean was 10 percent. The hydrolysis productivity of cellulose and phytase after the fermentation was 35.27 +/- 2.81 percent and 39.48 +/- 0.05 percent, respectively.