The invention discloses a bidirectional direct current converter based on an immittance network, and a digital control system and a digital control method of the bidirectional direct current converter. The bidirectional direct current converter based on the immittance network comprises a storage battery, a low-voltage-side filter capacitor, a first active full-bridge circuit, the immittance network, a high-frequency transformer, a second active full-bridge circuit and a high-voltage-bus-side filter capacitor. The digital control system comprises a first voltage sensor, a second voltage sensor, a current sensor and a digital signal processing (DSP) digital controller, wherein the DSP digital controller comprises a BUCK controller, a BOOST controller, a signal conditioner, a first selective switch and a second selective switch. According to the basic characteristics of the immittance network, the two active full-bridge circuits in the bidirectional direct current converter can operate with high power factor, and the current stress of a switching tube can be greatly reduced. By the adoption of the system and the method, according to the characteristics of the immittance network, the zero-current turn on and zero-current turn off of all switching devices of a high-voltage-side active full-bridge circuit are realized, and the efficiency of the converter is improved.