The invention discloses a method for synthesizing trans-cyclohexyldiamine. The method comprises the following steps: by using epoxy cyclohexane as the raw material, carrying out ring opening with ammonia water, adding sulfuric acid for dewatering and salification, adding free alkali, carrying out ring opening with ammonia water, and distilling to obtain the trans-cyclohexyldiamine. The method has the advantages of high repetitiveness of the synthesis route, and simple and accessible raw materials, and provides an alternative scheme for obtaining the trans-cyclohexyldiamine pure product.