Preparation method of nano beta-glucan

The invention relates to the technical field of beta-glucan preparation, in particular to a preparation method of nano beta-glucan. The preparation method comprises the following steps: sequentially carrying out autolysis, inactivation, protein removal, freeze thawing and grinding, enzymolysis and solubilization, and freeze drying on yeast, so as to finally prepare the nano beta-glucan. According to the method, autolysis is promoted by preparing the autolysis accelerant and the composite lysotrophin, so that the yield of beta-glucan is increased; in the protein removal step, neutral protease or alkaline protease is added to be compounded with papain, so that the protein removal rate is improved, and the purity of beta-glucan is further improved; in the step of freezing, thawing and grinding, yeast cell walls are mechanically broken through repeated freezing and thawing, then grinding is carried out, release of cell inclusions is further promoted, and the particle size of beta-glucan is reduced while the purit