The　spiral　groove　dry　gas　seal　is　designed　according　to　the　sealing　requirements　of　the　shaft　end　in　450　MWe　supercritical　CO2　(SCO2)　compressor.　The　influences　of　spiral　angle　and　groove　depth　on　the　sealing　performance　of　the　designed　dry　gas　seal　are　numerically　investigated　using　three-dimensional　Reynolds-Averaged　Navier-Stokes(RANS)equations　and　SST　turbulence　model.　The　accuracy　of　the　numerical　method　is　validated　by　comparison　of　the　experimental　data　for　dry　gas　seal　with　air　working　fluid.　The　leakage　flow　rate,　opening　force　and　opening　force　leakage　ratio　of　the　spiral　groove　dry　gas　seal　at　five　different　spiral　groove　depths　and　four　different　spiral　angles　are　numerically　analyzed.　The　results　show　that　the　increase　in　the　spiral　groove　depth　leads　to　an　intense　increase　in　the　maximum　pressure　and　the　high　pressure　area　in　the　groove　root　region　of　the　dry　gas　seal,　which　results　in　a　higher　opening　force　and　bigger　leakage　rate.　When　the　groove　thickness　increases　from　3　μm　to　7　μm,　the　maximum　increase　of　opening　force　is　9.07%　when　the　spiral　angle　is　20°;　the　maximum　increase　of　leakage　rate　is　18.67%　when　the　spiral　angle　is　25°.　The　maximum　opening　force　leakage　ratio　is　reached　when　the　spiral　groove　angle　is　15°,　which　means　the　dry　gas　seal　with　this　groove　angle　has　the　best　comprehensive　sealing　performance.　The　performance　analysis　of　the　spiral　groove　dry　gas　seal　at　the　shaft　end　of　the　compressor　in　this　study　provides　a　reference　for　the　SCO2　power　cycle　seal　design.　©　2020,　China　Food　Publishing　Company.　All　right　reserved.