Vehicle body connecting assembly, vehicle body structure and vehicle

The utility model relates to the field of vehicle body parts, and discloses a vehicle body connecting assembly, a vehicle body structure and a vehicle, the vehicle body connecting assembly comprises a vehicle body base plate (3), a transition base body (4) and an installation module (2), the transition base body (4) is connected to the surface of the vehicle body base plate (3) in a welded mode, and the installation module (2) comprises a module body (5) and a connecting plate (6) which are connected with each other. And the connecting plate (6) is connected to the transition base body (4). According to the technical scheme, the transition base body is additionally arranged, so that trepanning on the vehicle body substrate can be avoided, the sealing performance of the joint or the vicinity of the vehicle body substrate and the mounting module is improved, the waterproof performance is improved, and abnormal sound of the direct joint of the vehicle body substrate and the mounting module during movement can be