Abstract: A hydro-forming method for an aluminum alloy is provided which comprises: loading a tube component made of an aluminum alloy on a die of a hydro-forming apparatus; bringing a first die and a second die together in a state in which the tube component is loaded, and sealing and axially compressing the tube component by operation of a hydraulic cylinder disposed on each side of the tube component; heating the tube component to a temperature within a predetermined temperature range; forming the tube component along forming surfaces formed on the first die and the second die by providing an axial compressing force of the hydraulic cylinders and supplying hydraulic pressure into the tube component, when the tube component is heated to the predetermined temperature; and taking the formed tube component out of the first and second dies, and cooling the tube component.