The　antiferromagnetic　moments　in　the　topological　insulator/antiferromagnetic　insulator　bilayer　(Bi,Sb)(2)Te-3/alpha-Fe2O3　can　be　reversibly　switched　using　electrical　currents　at　room　temperature,　and　with　a　critical　current　density　that　is　one　order　of　magnitude　smaller　than　that　required　in　heavy-metal/magnetic　insulator　systems.　Antiferromagnetic　materials,　which　have　ordered　but　alternating　magnetic　moments,　exhibit　fast　spin　dynamics　and　produce　negligible　stray　fields,　and　could　be　used　to　build　high-density,　high-speed　memory　devices　with　low　power　consumption.　However,　the　efficient　electrical　detection　and　manipulation　of　antiferromagnetic　moments　is　challenging.　Here　we　show　that　the　spin　current　and　antiferromagnetic　moments　in　the　topological　insulator/antiferromagnetic　insulator　bilayer　(Bi,Sb)(2)Te-3/alpha-Fe2O3　can　be　controlled　via　topological　surface　states.　In　particular,　the　orientation　of　the　antiferromagnetic　moments　in　alpha-Fe2O3　can　modulate　the　spin　current　reflection　at　the　bilayer　interface.　In　turn,　the　spin　current　can　control　the　moment　rotation　in　the　antiferromagnetic　insulator　by　means　of　a　giant　spin-orbit　torque　generated　by　the　topological　surface　state.　The　required　threshold　switching　current　density　is　3.5　x　10(6)　A　cm(-2)　at　room　temperature,　which　is　one　order　of　magnitude　smaller　than　that　required　in　heavy-metal/antiferromagnetic　insulator　systems.