Abstract: Aluminum alloy A356 with uniform, fine and rose flowered grains was obtained by nearby liquidus semi-continuous casting method. The structure evolution of aluminum alloy A356 during remelting was studied by electron microscope. The results showed that when A356 alloy was heated at 585°C for 10~15 min, semi-solid thixotropic organization was obtained. The remelting temperature and the time of heat insulation affect the evolutionary process of the organization. And the growth and globe rate of α phase increase with the remelting temperature increasing, while the roundness increases with the time of heat insulation.