Abstract: In order to improve the refining and modification effect of A356 aluminum alloy, reduce the cost, carry melt mixing refining and modification on A356 aluminum alloy, and compared with traditional technique. The experimental results showed that the melt mixing refining and modification treatment has a better effect. In the process of the mutually melt mixing can fully for particles and energy exchange, the second phase particles spontaneously from higher chemical potential phase into the lower chemical potential phase，reduce the total free energy of system, make the system to achieve balance. Due to the change of the solute in the liquid phase concentration, change the equilibrium of the solute distribution coefficient K0, change its crystallization precipitation, reduce the enrichment of segregation of second phase particles, and significantly improve the refining and modification effect.