Yeast expression system is widely used in biomedical system, both the prokaryotic expression of the advantages of short fermentation cycle, low cost, at the same time have eukaryotic cells for the space of protein folding, glycosylation modification, such as ability, makes the protein to form natural stereo structure, to investigate the physiological activity of protein provides a powerful tool. Saccharomyces cerevisiae expression system and methanotrophic yeast expression system are commonly used. Methanol yeast expression system is the most widely used yeast expression system at present, compared with SACCHARomyces cerevisiae system, the expression level is higher and can be used for high density cell culture. At present, methanolyeasts mainly include Hansenula, Pichia, Torulopsis, etc. Pichia is a relatively perfect methanoltrophic yeast expression system developed in recent years, which is widely used to express exogenous proteins. The company has rich host cell resources and carrier selection experience, which can effectively increase protein expression while avoiding the generation of impurities and degradation of target protein. Our r & D personnel have rich experience in pichia pastoris expression system, which can maximize the expression potential of yeast strains and improve the success rate and expression level. At the same time, the target product was obtained with high yield and purity.