The　semi-solid　slurry　of　A319,　A356,　A380,　ZL203,　7075　aluminum　alloy　were　prepared　by　the　internal　cooling　process.　The　effects　of　the　stirring　speed,　the　mass　ratio　of　internal　cooling　block　to　aluminum　melt　and　the　temperature　of　aluminummelt　on　microstructure　of　A319　semi-solid　slurry　were　researched.　The　results　indicate　that　the　roundness　of　the　primaryparticles　and　grain　refinement　effects　can　be　increased　with　the　increasing　of　stirring　speed.　The　well　globular　primary　α-Al　was　produced　when　the　mass　ratio　of　internal　cooling　block　to　aluminum　melt　was　3%,　temperature　of　aluminum　melt　was　615　℃　and　the　mass　ratio　of　internal　cooling　block　to　aluminummelt　was　5%,　temperature　of　aluminummelt　was　615-625　℃,　in　which　the　average　diameter　and　shape　factor　of　the　primary　α-Al　particles　was　61-71　μm　and　0.68-0.73　respectively.　The　process　of　nucleation　and　growth　of　the　spheroidal　primary　α-Al　during　the　internal　cooling　process　were　analyzed.　©　2016,　Chinese　Mechanical　Engineering　Society.　All　right　reserved.