The invention discloses a charger for motor vehicle mutual charging through live wire connection. The charger for motor vehicle mutual charging through live wire connection comprises a transformer, a charger power source converting driving switching circuit and a closed-loop control circuit and further comprises an input reversed-connection protection circuit, an output high-voltage low-voltage automatic switching circuit and an output reversed-connection protection circuit, wherein the input reversed-connection protection circuit is in parallel connection with the charger power source converting driving switching circuit and is connected with the two ends of a transformer primary coil, the output high-voltage low-voltage automatic switching circuit is in parallel connection with the closed-loop control circuit and is connected with the two ends of a transformer secondary coil, the input end of the output reversed-connection protection circuit is connected with the output end of the output high-voltage low-voltage automatic switching circuit, and the output end of the output reversed-connection protection circuit is connected with the output end of the charger. According to the charger for motor vehicle mutual charging through live wire connection, mutual charging of the charger power source converting driving switching circuit and the closed-loop control circuit which are mutually independent is achieved and revered-connection protection of a power source and a battery is achieved.