The invention discloses a deformable yoke pressing-ironing lower die, which comprises a die frame (1). The die frame (1) is provided with a main die (2) of which the shape is adaptive to that of a yoke; the die frame (1) at the positions of left and right chuck rings and a neck ring of the main die (2) is provided with a plurality of auxiliary dies (3); and the auxiliary dies (3) can be combined or separated with the main die (2) to form die surfaces adaptive to clothes yokes of different yards. According to the shape changes of different yards at the position of the shirt yoke, a change areais divided into different auxiliary dies, and the auxiliary dies are combined or separated with the main die to form the die surfaces adapted with the clothes yokes of different yards. When clothes ofdifferent yards and styles are pressed and ironed, a preset yard or style program is selected on a control box, and the die automatically changes to the corresponding shape and size under the drivingof motion of a pneumatic or electric element, so the operation is convenient and quick. Therefore, the cost and time for replacing the die are greatly saved, and the utilization rate of a machine isimproved.