Abstract: A vacuum plastic molding machine includes a heating device, a plurality of upright posts, a carrier assembly, and a demolding mechanism. The carrier assembly includes an upper carrier and a lower carrier. The upper carrier includes an upper frame, multiple upper movement structures, at least one rotation plate, at least one driving member, and at least one linking mechanism. An adjusting space is defined between the at least one rotation plate and the at least one linking mechanism. The lower carrier includes a lower frame, multiple lower movement structures, and at least one locking tenon. The locking tenon is placed into the adjusting space. The at least one driving member is rotated to change the position of the at least one locking tenon in the adjusting space, and to adjust the distance between the upper carrier and the lower carrier.