The invention discloses an automobile crash box, relates to automobile accessories and provides an energy absorbing device which is uniform in deformation and good in crash energy absorbing effect. The automobile crash box in the embodiment comprises a tubular crash box body, one end of the crash box body is provided with a front mounting plate connected with an anticollision beam of an automobile, and the other end of the same is provided with a rear mounting plate connected with a longitudinal beam of the automobile. The side wall of the crash box body is provided with crumple grooves recessed inwardly, and at least one guide plate is fixed on at least one side wall of the crash box body and provided with a weakening structure corresponding to the crumple grooves. When automobiles crash, the weakening structures of the guide plates can deform and guide the crumple grooves to crumple and absorb energy. The automobile crash box is mainly applied to automobiles.