A tubing bulging device and a method using internal heating and pressing relate to a tubing bulging device and a method. The tubing bulging device and the method are used for solving problems that during the thermal state bulging process in existing tubings, shape and size changes of a mould cavity are easily caused by heat expansion and cold contraction, and the plastic deformation of a whole mould is easily caused by the fact that the mould strength is reduced. The device includes that a left die block and a right die block are parallelly arranged on a lower seal base from left to right in a sealing mode, an upper seal base is disposed at the upper ends of the left die block and the right die block, and an air feeding hole is mounted on the upper seal base. The method includes that a formed cavity is formed by the left die block and the right die block, two ends of a tube blank are sealed, the tube blank is heated by a heating unit to reach a set forming temperature, high pressure gases are fed into the tube blank, the heating is stopped when the tube blank is completely attached to the mould and maintained for some time, then the high pressure gases in the tube blank are released, a formed tube fitting is obtained, and the tubing bulging is completed. The tubing bulging device and the method using internal heating and pressing are applied to tubing bulging.