)Abstract:Rawlsdistinguishedtwokindstheoriesofgood,whicharethethicktheoryofgoodandthethintheoryofgood.Thefoundationofthethicktheoryofgoodistheprincipleofright,whichwasdiscussedwidelyintheframeofdeontologymeaningthatrightispriortogood.Ontheotherside,thecorecategoryofthethintheoryofgoodistheprimarygoodandRawlsestablishedhisstartingpointofpracticalreasoning.Andthetheoryofgoodhasn謖tgainedenoughdiscussionbecauseitisoutoftheframeworkofdeontology.thetheoryofjustice.ButthetheoryofprimarygoodisunavoidableinInthebook,thattheoryhastwoexistentlevels.Firstly,itisthestartingpointforRawls謖practicalreasoning;secondly,ifthethintheoryofgooddoesnotexist,itishardforthetwoprinciplesofrighttogainitssufficientstabilityinthelevelofmorality.Keywords:thethintheoryofgood;theprimarygoods;theprincipleofright;stability