The utility model relates to the technical field of underwear, in particular to adjustable underwear, an unfolding structure of the adjustable underwear comprises two mold cups in
bilateral symmetry, side parts and rear parts, each side part comprises a side part
surface layer and a side part inner layer, the mold cups are sewn with the side part inner
layers, the side part surface
layers extend upwards to form front outer shoulder straps, and the rear parts extend upwards to form rear outer shoulder straps. The front outer shoulder strap is sewn with the rear outer shoulder strap, the front inner shoulder strap is sewn on the inner surface of the sewing position of the front outer shoulder strap and the rear outer shoulder strap, the other end of the front inner shoulder strap is sewn with the inner layer of the side piece, the rear piece and the
surface layer of the side piece are made of continuous cloth, and the sides, away from the side piece, of the two rear pieces are respectively provided with a rear row hook and a rear row ring which can be buckled with each other; the outer surface between the front outer shoulder strap and the rear outer shoulder strap is further sewed with an American shoulder strap, the top end of the American shoulder strap extends towards the left side and the right side to form front connecting straps, and the two front connecting straps are provided with a front row hook and a front row ring which can be buckled with each other respectively. The back beautifying belt guides trapezius muscles and rhombus muscles to retract backwards and sink through pressure, the humpback is corrected, and the forerake posture of the head is improved.