The work aims to improve the deinking efficiency of mixed office waste paper cellulase. Cellulase was used in office waste paper deinking. Based on the analysis of deinking pulp whiteness and ink removal rate, the optimum process conditions were concluded. The best process for deinking of mixed office waste paper cellulase was to add the OS-15 with cellulase Novozyme 476 for deinking, the best dosage (mass fraction) of surfactant was 0.75%, the pulp concentration (mass fraction) was 6%, the pH value was 8.5, the processing temperature was 55 ℃, the processing time was 60 min, and the amount of cellulose was 2 U/g. The enzymatic deinking efficiency has been significantly improved with the surfactant added to the cellulose.