The invention discloses an adjustable blood drawing auxiliary support. The adjustable blood drawing auxiliary support comprises a base. A movable tank is arranged at the top end in the base. A first threaded rod is arranged in the movable tank, the surface of one end of the first threaded rod is sleeved with a movable block, a fixed column is arranged on the top of the movable block, a movable column is arranged on the top of the fixed column, and a second threaded rod is arranged in the movable column. The fixed column, a first linear motion bearing, a rotary plate, the second threaded rod and the movable column are arranged and matched for use, the height of a fixing frame plate is conveniently adjusted, and the advantage that the hands, at different heights, of patients can be effectively fixed is enhanced. The fixing frame plate, an installing plate, a memory cotton block, a bearing block, a second linear motion bearing, a third threaded rod, a rotating plate and a spring are arranged and matched for use, motion of the memory cotton block is achieved, and the advantages that the arms, with different thicknesses, of the patients can be effectively fixed and the tightening state of the arms of the patients can be relieved are enhanced.