The present paper intends to introduce the authors' research on the best cultivation conditions of the mixed cellulolytic strains to produce cellulase.In doing so,the six cellulolytic strains were screened out from nature,which should be isolated with no mutual amensalism.And then the strains were let to be co-fermented.The optimum conditions for co-fermentation prove to be as follows: cassava residue 4 g,soybean powder 0.75 g,KH_2PO_4 0.20 g,NaCl 0.02 g,MgSO_4·7H_2O 0.015 g;initial pH=7.0,temperature 40 ℃,...