Width-adjustable auxiliary frame and concrete mixing truck

The utility model relates to a width-adjustable auxiliary frame and a concrete mixing truck, the width-adjustable auxiliary frame comprises a first main beam, a second main beam parallel to the first main beam, and an adjusting device adjustably connected with the first main beam and the second main beam, the two ends of the adjusting device are perpendicularly connected with the first main beam and the second main beam respectively, and the adjusting device comprises an adjusting rod used for adjusting the width of the auxiliary frame, a plurality of installation areas arranged in the long axis direction of the adjusting rod and a connecting piece used for fixing the adjusting rod. And the connecting piece selectively fixes the adjusting rod through the mounting area. According to the auxiliary frame with the adjustable width, the width can be adjusted according to the loading of an engineering vehicle and the size of a chassis, the applicability is improved, the damage to the structure of the auxiliary fram