The utility model provides a pin block limiting device for an automobile rear cross beam, which comprises a limiting plate, wherein the limiting plate comprises a connecting section and a limiting section, both of the two sections are shaped through integrated bending of panels, and this structure can ensure that the limiting plate and a rear cross beam plate have relatively high strength and rigidity and can effectively prevent cracking of the two parts. Length of the limiting section is bigger than that of the connecting section, a guiding bend is disposed at one end in the limiting section which is opposite to the connecting section and the guiding bend can ensure that a pin block will not violently impact the limiting plate when the pin block is deviated from a limiting track to an extent and the pin block can slowly enter a running track of the pin block. A reinforcing plate is disposed on an external side face of the limiting section, wherein the reinforcing plate can increase the rigidity of the limiting plate and prevent the cracking thereof. The connecting section of the limiting plate is welded to a rear cross beam late in order to lift the rigidity of the rear cross beam plat and can effectively prevent the cracking at a long grooving place of the rear cross beam plate.