The invention discloses a portable foldable vehicle-mounted trash can. The trash can comprises a can seat, a bagging box, a support rod, a fixing ring, a hook and a height adjusting device, wherein two fixed instillation buckles are arranged at the inner side of the can seat, a retaining box and an installation shaft are arranged at the upper end and the lower end of the support rod respectively, the two ends of the installation shaft are inserted into the installation buckles, the bagging box is arranged in the middle of the can seat, the fixing ring is connected with the height adjusting device, the hook is arranged on the height adjusting device, the upper portion of the fixing ring is provided with saw teeth, the front portion of the fixing ring is provided with a bag clamping hole, and the can seat and the fixing ring are both foldable. According to the portable foldable vehicle-mounted trash can, the fixing ring is provided with the bag clamping hole and the saw teeth so that a trash bag can be fixed, and by means of the simple mode, the problem that the trash bag slides down is well solved; in addition, the trash can is further provided with the height adjusting device, the height of the trash can can be adjusted according to the size of the trash bag, and the user requirements are further satisfied in a better mode.