Disassembly　plays　an　important　role　in　the　production　process.　Screw　automatic　unfastening　guided　by　a　robot　has　been　widely　used　in　the　fields　of　industrial　manufacturing　and　maintenance.　Different　from　the　previous　studies　that　have　used　a　flexible　effector　and　expensive　sensors,　this　paper　presents　a　novel　unfastening　strategy　based　on　robot　vision　for　a　hexagonal　screw　with　an　arbitrary　loose　state.　In　a　robotic　system,　an　industrial　camera　and　a　servo　unfastening　tool　are　installed　at　a　robotic　end-effector.　The　main　contributions　of　this　work　are　as　follows.　A　camera　pose　adjustment　method　is　proposed　to　obtain　high-quality　images　of　a　target　screw.　The　hexagonal　screw　pose　calculation　method　based　on　the　geometric　analysis　is　developed　to　complete　the　screw-tool　engagement.　The　cooperated　motion　of　a　robot　and　an　unfastening　tool　is　planned　for　the　screw　unfastening　action.　The　effectiveness　of　the　proposed　control　strategy　is　verified　by　experiments,　and　the　influence　of　the　motion　speed　on　the　unfastening　quality　is　analyzed　using　the　torque　data　collected　by　the　unfastening　tool.　The　analysis　results　can　provide　a　significant　foundation　for　the　motion　parameter　selection　in　the　proposed　strategy.