Abstract: Cellulase is a compound enzyme that can hydrolyze the cellulose into glucose. It has been widely used in many fields, including biological transformation, food and textile industries and other fields. It is extremely of important significance to study on cellulase molecular modification, which can solve the big global issues (such as energy crisis, environmental pollution, food shortage et al). This paper describes some molecular modification technologies of celluase, such as site-directed mutagenesis, error-prone PCR, DNA shuffling et al. The research has great significance for cellulase production and further research.