The invention provides a bidirectional DC converter and a control method of bidirectional DC conversion. The bidirectional DC converter comprises a first chopping unit, a second chopping unit, a transformer, a voltage detection unit and a control unit, wherein the second chopping unit is connected to a positive bus and a negative bus, a first capacitor is arranged between the positive bus and thenegative bus, a second inductor and a second capacitor are connected in series between an intermediate tap of a secondary winding of the transformer and the negative bus, two ends of the second capacitor are connected to a second external terminal, and the control unit is used for adjusting a duty ratio of a pulse width modulation signal output to a control end of the first chopping unit accordingto a voltage of the second external terminal until a voltage measured by the voltage detection unit reaches a preset value when energy flows to the second external terminal from the first external terminal. By the bidirectional DC converter, high-efficiency energy transmission can be ensured when the bidirectional DC converter possess a relatively large transmission ratio change range.