The effect of Al-3Ti-0.2C-5Sr (wt％) grain refiner on the refining performance and modification of A356 alloy was investigated using optical microscope (OM).The morphology and crystal structure of ternary Al-Ti-Sr phases in Al-3Ti-0.2C-5Sr refiner were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The results show that the ternary Al-Ti-Sr phases in Al-3Ti-0.2C-5Sr refiner can promote the grain refining efficiency of A356 alloy.The ternary Al-Ti-Sr phases co-exist in two morphologies,i.e.,blocky-like phase and surround-like phase,besides,which both have the same chemical composition of Al34Ti3Sr.The crystal structure of Al34TiaSr is face-centered cubic,and the lattice parameter is determined to be about 1.52 nm.