Helicity-dependent　photocurrent　(HDPC)　has　been　observed　in　epitaxial　thin　films　of　the　three-dimensional　topological　insulator　Sb2Te3　with　a　thickness　of　7,　20,　and　30　quintuple　layers　(QLs).　By　analyzing　the　incident　angle　dependence　of　the　HDPC,　we　successfully　extract　the　photocurrent　induced　by　the　circular　photon　drag　effect　(CPDE)　of　even　parity　from　the　HDPC.　It　is　found　that　the　circular　photogalvanic　effect　(CPGE)　is　larger　than　the　odd　parity　of　CPDE.　The　CPGEs　of　the　top　and　bottom　surface　states　are　successfully　distinguished　at　room　temperature.　As　the　thickness　of　the　Sb2Te3　film　is　increased　from　7　to　20　QLs,　the　dominant　contribution　of　the　CPGE　current　switches　from　the　top　surface　states　to　the　bottom　surface　states　under　the　front　illumination　of　a　1064-nm　laser.　Additionally,　it　is　found　that　the　CPGE　currents　of　the　20-　and　30-QL　samples　reverse　sign　when　the　temperature　is　increased　from　77　to　300　K,　which　may　be　attributed　to　the　HDPC　current　induced　by　the　combined　action　of　the　inverse　spin　Hall　effect　and　the　vertical　thermoelectric　effect　overwhelming　the　CPGE　current　at　low　temperature　in　the　samples.　The　insights　we　obtained　are　significant　for　engineering　optospintronic　devices　based　on　three-dimensional　topological　insulators　with　a　strong　thermoelectric　effect.