As　a　common　athletics　injury,　the　rehabilitation　of　ankle　injury　is　a　long　and　arduous　process.　The　trajectory　planning　for　the　ankle　rehabilitation　during　the　rehabilitation　process　plays　an　important　role　to　avoid　a　secondary　ankle　injuring.　For　this　purpose,　a　nutation　principle　based　trajectory　planning　method　is　proposed　for　a　novel　hybrid　ankle　rehabilitation　device　composing　of　a　series　and　a　parallel　mechanism.　The　nutation　angle　is　determined　by　the　biomechanical　simulation　results　of　the　muscle　activity　in　AnyBody　software　according　to　the　safety　requirements　for　ankle　rehabilitation　exercise.　On　this　basis,　an　inverse　kinematic　analysis　is　carried　out　to　calculate　the　displacement　of　the　pushrods.　Finally,　an　experimental　prototype　of　the　proposed　hybrid　rehabilitation　device　is　built　and　the　nutation　motion　of　the　platform　is　measured　with　a　laser　tracker.　The　comparison　between　the　theoretical　derived　and　the　experimental　tested　data　confirms　that　the　proposed　nutation　motion　based　trajectory　planning　can　fulfill　the　plantar/dorsal　flexion　and　inversion/eversion　movement　and　meet　the　safety　requirements　of　ankle　rehabilitation　exercise.　Therefore,　the　proposed　hybrid　ankle　rehabilitation　device　and　the　nutation　rehabilitation　trajectory　can　provide　an　effective　solution　for　ankle　injury　rehabilitation.　©　2018　Journal　of　Mechanical　Engineering.