Battery box body, battery pack and vehicle

The utility model discloses a battery box body, a battery pack and a vehicle. The battery box body comprises a first side beam and a baffle plate, a first cavity is formed in the first side beam, a first cavity wall of the first cavity is formed on one side, facing the interior of the battery box body, of the first side beam, a first communicating hole penetrating in the thickness direction of the first cavity wall is formed in the first cavity wall, and a first exhaust hole is further formed in the first side beam, so that the first cavity is communicated with the exterior of the first side beam; the baffle plate is arranged at the exhaust port of the battery box body, and forms an exhaust space with the inner wall of the battery box body in a surrounding manner; and the first exhaust hole and the exhaust port are respectively communicated with the exhaust space. And the gas generated by the battery cell is discharged through the first cavity, and the gas discharged by the first cavity is prevented from bein