The invention discloses a high-gain bidirectional four-phase DC-DC converter based on a coupling inductor and a control method. The converter comprises the four-phase coupling inductor, eight power switch tubes S1 to S8 and five capacitors CL, C1, C2, CH1 and CH2, wherein the inductance of all phases of the coupling inductor includes inductance L1 to L4, the coupling mode is a positive-negative coupling mode, and that is to say, positive coupling is realized between odd-number phases and between even-number phases of the coupling inductor and negative coupling is realized between the odd-number phases and the even-number phases. The converter has a higher voltage conversion ratio, and the voltage conversion ratio of the converter can be increased to be four times that of a traditional bidirectional four-phase DC-DC converter; the power switch tubes have lower voltage stress, the voltage borne when the power switch tubes S2, S4 and S6 are turned off is one half of the high-voltage sidevoltage, and the voltage borne when the power switch tubes S1, S3, S5, S7 and S8 is one fourth of the high-voltage side voltage.