Abstract: The effects of barium chloride additions, metamorphoic temperatures and cooling rates on microstructure and mechanical properties of as-cast Al-Si-Mg alloy metamorphosed by barium chloride was studied. The results show that the metamorphic effect of the tested alloy was more obvious with the increase of barium chloride adding content, but too much barium chloride was bad to the microstructure and mechanical properties of the alloy. Increasing cooling rate was benefit for metamorphoic effect. The best barium chloride metamorphic temperature was about 750 ℃ and the best barium chloride addition was 1.0wt%, and the long holding property and re-melting stable property of barium chloride metamorphosing was good.