Provided in the present invention is a method for preparing a β-nucleoside compound, comprising the steps of: 1) performing a silylation reaction of a nitrogenous base or an analogue thereof in the presence of TMSOTf to obtain the nitrogenous base or the analogue thereof being protected by trimethylsilyl; 2) performing a direct glycosylation reaction of the reaction liquid, without being isolated, and a five- or six-membered ring saccharide or a derivative thereof closed by a hydroxy protecting group to obtain a closed β-nucleoside compound; and 3) performing a deprotection reaction to obtain the β-nucleoside compound. The method uses a one-pot process to prepare the key intermediate of the β-nucleoside compound, and the yield of the β-configuration substance increases significantly. The method has the advantages of a simple operation, saving energy and protecting the environment, and is suitable for industrial application.