In order to overcome the shortcomings of slow energy transfer and large volume of the traditional aircraft bidirectional DC conversion system, a bidirectional DC conversion system suitable for the power supply system of multi-electric aircraft is designed. This system takes DSP as the control core and bidirectional full-bridge DC converter as the main circuit, and introduces its software and hardware design. Under laboratory conditions, a two-way DC conversion system of 25 V-5 V is made and tested. The test results show that the system can realize the digital control of the bidirectional full-bridge DC converter, and has the characteristics of simple structure, electrical isolation, and small volume and weight.