The invention belongs to the technical field of organic chemistry, and particularly relates to a method for preparing acetylated glycal, acetylated disaccharide glycal and benzoylated glycal. Acetylated glycosyl bromide or acetylated disaccharide bromide or benzoylated glycosyl bromide is added into a system of PEG and water, and then Zn powder is added to carry out room temperature reaction to respectively generate the acetylated glycal or the acetylated disaccharide glycal or the benzoylated glycal. The invention has the advantages of simple operation, short process, high yield, fast reaction, low cost, fewer three wastes, energy saving, environment protection, easy industrialization and the like.