The utility model relates to a self-adaptive adjustable anti-blocking safety device for a motorcycle. The upper end of an upper shell body 1 is provided with a circular hole transversely, a connecting screw bolt 7 is penetrated in the circular hole, and the connecting screw bolt 7 and a sulfuration cushion ring 8 are sealed firmly by screw nuts. The interior of the circular hole of the shell body 1 is provided with an upper through hole 11 and a lower through hole 11 which are vertical to the connecting screw bolt 7. Thg upper hole 11 is communicated with a deflating valve 6, and the lower hole 11 is communicated with a capsule 2. Both the upper through hole 11 and the lower through hole 11 are communicated with a vertical through hole 13 of the connecting screw bolt 7. An inner cavity is arranged in a lower shell body 4. The capsule 2 and a rubber spring 3 are arranged in the inner cavity. The rubber spring 3 is tightly pressed by the capsule 2 and an adjusting screw 9. The adjusting screw 9 is tightly locked by a locking screw nut 10. The utility model has the advantages of simple structure, easy overhauling, and good self-adaptive effect.