The present application provides a battery box, including a lower box body. The lower box body includes: a first plate including a bottom wall and a peripheral wall that is connected to the peripheral edge of the bottom wall and extending upwards, where the bottom wall and the peripheral wall together form an accommodating space that opens upwards along a height direction; and a second plate that is fastened under the bottom wall and that forms, together with the bottom wall, an inlet flow path, an outlet flow path, and a main flow path communicating with both the inlet flow path and the outlet flow path, where the main flow path includes a first main flow path, a second main flow path, and a plurality of parallel branch flow paths that communicate with both the first main flow path and the second main flow path.