The present invention discloses a method for efficiently and mildly reducing ovalbumin allergenicity. The present invention promotes the exposure of the ovalbumin allergenic site to the molecular surface by repeated freezing and thawing pretreatment, and combines transglycosylase and trypsinase for synergistic treatment to reduce the ovalbumin sugar chain and epitope to achieve the purpose of significantly reducing the allergenicity of ovalbumin and egg foods. Compared with other traditional methods such as high temperature and high pressure and other physical means to reduce egg allergenicity, the method significantly improves the specificity and effectiveness of egg desensitization, and minimizes the damage to the nutrition and quality of egg proteins, and is an efficient and mild egg desensitization method. The method has the prospects of being applied to the industrial development of low-allergenicity egg products.