A brake cylinder adjustment assembly for adjusting brake cylinders of different sizes and includes a rotation unit and a driving unit which is connected with the rotation unit. The rotation unit includes a rotatable disk, a fixed disk, at least two positioning rods and a clip. The rotatable disk has at least two curved slots and the fixed disk has at least two slide slots. The at least two positioning rods are engaged with the at least two slide slots and the at least two curved slots. The brake cylinder adjustment assembly uses a single driving unit and single rotation unit to adjust the left and right brake cylinders of different sizes.