Variable cross-section vehicle body structure

The invention discloses a variable cross-section vehicle body structure which comprises a front frame, first fixing pipes are welded to the two ends of the front frame correspondingly, supporting assemblies are arranged on one sides of the first fixing pipes correspondingly, the supporting assemblies are distributed in the middles of the two sets of first fixing pipes at equal intervals, and sleeves are arranged on the outer walls of the first fixing pipes. A third fixing pipe is welded to the outer wall of the bottom of the sleeve, a reinforcing plate is welded to the bottom of the third fixing pipe, a second fixing pipe is welded to the outer wall of the bottom of the reinforcing plate, and the pipe diameter of the third fixing pipe and the pipe diameter of the second fixing pipe are gradually increased from top to bottom. The bearing capacity and stability of the bottom of the whole vehicle body can be effectively improved, variable cross-section arrangement of the vehicle body structure is achieved, the p