The invention discloses a fine design method for a voltage and current transmission ratio of a high-frequency transformer. The method comprises the steps of A, building a voltage and current transmission function of the high-frequency transformer, and acquiring transmission characteristic resonant property; B, proposing design constraint of the transmission ratio of the high-frequency transformer; and C, achieving design of the transmission ratio of the high-frequency transformer. By the method, the voltage and current transmission ratio of the high-frequency transformer can be approximate to a turn ratio of a winding, so that expected voltage and current conversion of the high-frequency transformer is enabled to be achieved, and the method has certain guidance significance to optimal design of the high-frequency transformer.