The　semi-solid　alloy　slurry　of　Al-7Si　alloy　was　prepared　by　the　internal　cooling　type　mixing　stirring　method.　The　effects　of　different　melt　stirring　initial　temperature,　ratio　of　internal　cooling　mixing　block,　stirring　rate　and　sampling　temperature　on　semi-solid　microstructure　and　average　grain　size　as　well　as　the　shape　factor　of　the　primary　α-Al　in　the　Al-7Si　alloy　were　investigated.　The　mechanism　of　forming　fine　near-spheroids　by　internal　cooling　mixing　methods　was　described.　The　results　reveal　that　with　the　melt　stirring　initial　temperature　of　625℃,　and　ratio　of　mixing　block　of　5%,　the　stirring　rate　of　1　200r/min　and　the　sample　temperature　of　600℃,　the　semi-solid　slurry　with　near-spherodized　primary　α-Al　can　be　obtained,　where　the　average　grain　size　and　the　shape　factor　reach　64.21　μm　and　0.649　0,　respectively.　©　2017,　Journal　Office　of　Special　Casting　and　Nonferrous　Alloys.　All　right　reserved.