The present invention provides a method for preparing atosiban acetate. The method comprises the following steps of: synthesizing to obtain linear atosiban； dissolving the linear atosiban in an acetonitrile aqueous solution, adjusting the pH value with ammonia water, adding H2O2 for oxidizing, filtering, purifying, and transferring salt to obtain the atosiban acetate. In the present invention, an appropriate route is provided, the linear atosiban is synthesized by adopting a solid phase method, and the atosiban is obtained by liquid phase oxidation. The method has the advantages of capabilities of solving the problem of insolubility of the linear atosiban, reducing the reaction size to the maximum extent and shortening reaction time, and being high in yield and easy to industrialize.
