A multifunctional vehicle-mounted refrigerator with a plug-in battery, comprising a refrigerator box, an openable cover arranged on a top of the refrigerator box, a refrigerating chamber and a freezing chamber that are arranged side by side in the refrigerator box, and a compressor that is installed at a bottom of one side of the refrigerator box; wherein the vehicle-mounted refrigerator further comprises two rollers arranged at one end of the bottom of the refrigerator box and a telescopic pull rod arranged at another end of the refrigerator box; wherein a battery chamber is defined in a side wall of the refrigerator box, and a battery is inserted into the battery chamber, characterized in that the battery comprises a battery box and a battery cover arranged at an upper end of the battery box, wherein laterally movable buckle plates are symmetrically arranged between two ends of the battery cover, wherein two ends of the buckle plates extend out of respective ends of the battery cover, a central portion of the buckle plates is disposed outside the battery cover, and the buckle plates at both ends are connected by an elastic piece, which is disposed in a limiting groove defined in an inner side of the battery cover, wherein a conductive socket is arranged in the battery chamber, and a conductive plug disposed on a side of the battery box is plugged into the conductive socket, wherein at least one groove is defined in an inner side wall of the box cover, and a detachable fruit cutting board is embedded in the at least one groove, wherein a rotating blocking plate is installed at one end of the at least one groove, and a convex plate is installed on a side wall at another end, wherein both ends of the fruit cutting board are restricted in the groove by the rotating blocking plate and the convex plate, and an inner bottom surface of the groove is evenly distributed with raised blocks. wherein the vehicle-mounted refrigerator further comprises two rollers arranged at one end of the bottom of the refrigerator box and a telescopic pull rod arranged at another end of the refrigerator box; wherein a battery chamber is defined in a side wall of the refrigerator box, and a battery is inserted into the battery chamber, characterized in that the battery comprises a battery box and a battery cover arranged at an upper end of the battery box, wherein laterally movable buckle plates are symmetrically arranged between two ends of the battery cover, wherein two ends of the buckle plates extend out of respective ends of the battery cover, a central portion of the buckle plates is disposed outside the battery cover, and the buckle plates at both ends are connected by an elastic piece, which is disposed in a limiting groove defined in an inner side of the battery cover, wherein a conductive socket is arranged in the battery chamber, and a conductive plug disposed on a side of the battery box is plugged into the conductive socket, wherein at least one groove is defined in an inner side wall of the box cover, and a detachable fruit cutting board is embedded in the at least one groove, wherein a rotating blocking plate is installed at one end of the at least one groove, and a convex plate is installed on a side wall at another end, wherein both ends of the fruit cutting board are restricted in the groove by the rotating blocking plate and the convex plate, and an inner bottom surface of the groove is evenly distributed with raised blocks.