Cellulase can evidently incerase th content of glucose and has a singiflicant effect on the production of citric acid from apple pomace by Aspergillus niger. Based on experiments, a cellulolytic enzyme named cellulase A6 was found able to produce about 170g glucose from 1kg dried apple pomace after 12h reaction, with cellulase comcentration of 20U/g the medium at 50℃, natural pH without pretreatment of alkali. Using the treated apple pomace as a liquid apple pomace at 35℃ in 3d or 30℃ in 5d with flask rotation speed of 210r/min, and the conversion of citric acid could reach 80% based on the amount of sugar consumed.