Single　crystal　Ni-based　superalloys　are　the　typical　structural　materials　for　high-pressure　turbine　blades,　and　their　microstructure　is　critical　in　determining　their　mechanical　properties.　The　withdrawal　rate　is　a　key　parameter　affecting　the　microstructure　during　the　single　crystal　growth　process.　In　the　present　work　the　effect　of　the　withdrawal　rate　on　the　microstructure　of　a　third-generation　single　crystal　superalloy　containing　6.8　wt%　Re　has　been　investigated,　and　the　creep　resistance　of　the　alloy　determined.　The　results　showed　that　increased　withdrawal　rate　refined　the　dendritic　structure,　reduced　dendritic　arm　spacing,　promoted　the　growth　of　secondary　tertiary　dendrites　and　decreased　solidification　segregation　with　a　reduced　size　of　gamma＇　phase.　The　porosity　density　of　the　ascast　alloy　first　decreased　and　then　increased　with　the　withdrawal　rate,　while　the　minimum　porosity　densityoccurred　when　the　alloy　was　under　the　solidification　condition　of　withdrawal　rate　of　4.5　mm/min.　The　maximum　creep　rupture　life　of　326.4　h　of　the　heat-treated　alloys　under　the　test　condition　of　1100　degrees　C/140　MPa　also　appeared　at　the　alloys　under　the　withdrawal　rates　of　4.5　mm/min.　It　is　believed　that　the　minimum　porosity　density　and　reduced　size　of　the　gamma＇　phase　may　be　the　main　reasons　for　the　enhanced　creep　rupture　life　of　the　alloys　with　withdrawal　rates　of　4.5　mm/min.　This　investigation　provides　theoretical　support　and　a　practical　basis　for　the　development　of　third-generation　single　crystal　superalloys.