The semi-solid ZA27 alloy which of the refined and well-distributed grain can be obtained by stirring with ultrasonic installing.The effects of starting temperature of ultrasonic application （i.e.Melt Superheating） and application time of ultrasonic stirring on microstructure of ZA27 alloy were investigated.The result revealed that the grain size tends to be increased with increasing the starting temperature of ultrasonic application.And there is an appropriate application time of ultrasonic stirring that the grain is to be better refined and distributed.Then when the time is more long

primary α-Al phase is easy to get together and grow much large.And also the application of ultrasonic stirring can decrease the tends of the earlier crystals’ getting together and can make the grain well-distributed.