It is not clear whether there is reinforcement inside the longitudinal beam, and the crack will continue to expand from the outside. The outside should be reinforced with steel plates and then painted with antirust paint. If the main girder is seriously deformed, we need to fix the tensioning position with a suitable fixture, and then straighten the deformed main girder and stretch it in the opposite direction of the main girder deformation. Repair method of vehicle rear longitudinal beam: 1. Correction method and equipment preparation of automobile girder. First of all, we need to prepare the equipment needed to correct the girder. Beam straightener, several fixtures, a small hammer, a middle hammer and several tools. Then, check whether the whole beam machine is clean and free of sundries, and drive the damaged car to the whole beam machine. 2. Fixation of the car. Fixing the four tires of the automobile with clamps to avoid dragging the automobile when stretching the main beam, rotating the straightening and stretching arm to the position of the main beam, and then fixing the lower part with clamping pins to avoid shaking and shaking of the stretching arm during stretching, thus fixing the straightening and stretching arm with the main beam. 3. Determine the deformation degree of the main girder. For smaller ones, we just need to stretch in the opposite direction of deformation. To find a measuring point on the car body while stretching, it is necessary to measure the diagonal lines with a box ruler, and stop when the two diagonal lines are stretched to the same length.