Abstract: In a self-designed pressure tank with a temperature measuring instrument, the authors made experiments on the pressurized casting of Al-Cu alloy and studied how the mechanical properties of the cast were affected by the time of pressurization and the exertion of pressure. The result of the experiments indicates that the pressurized casting greatly intensifies the toughness of the cast. The article also introduces a prac-fical and feasible method which can be used to improve the mechanical properties of the cast whenever it is pressurized.