The invention relates to an anthrax capsule surface carbohydrate antigen-based novel trisaccharide 4-methoxyphenoside compound and a preparation method thereof. The structural formula of the trisaccharide 4-methoxyphenoside compound is shown in the description; and in the formula, R1 is an acetyl group, R2 is a benzyl group, R3 is an acetamido group, and the end position is a p-methylphenoxyl group. The compound can be used for preparing oligosaccharide-like conjugates, can be used for synthesis reaches of anthrax carbohydrate vaccines, has the advantages of concise synthesis route, simplicity in operation, low raw material cost, strong versatility, and good glycosylation reaction stereoselectivity, and is suitable for synthesizing various oligosaccharide compounds.