BATTERY PACK HOUSING, BATTERY PACK AND VEHICLE

A battery pack housing includes a tray, a middle beam, a cover plate and a mounting member. The tray includes a bottom plate and a plurality of side beams and forms a receiving space for accommodating a battery unit. The receiving space is open at one side. The cover plate is configured to close the open side of the receiving space. The plurality of side beams include two first side beams opposite to each other. The middle beam is in the receiving space and two ends of the middle beam along a length direction are respectively spaced by a predetermined distance from or in contact with the two first side beams.