Bio-inspired　mechanism　not　only　needs　to　be　able　to　reproduce　the　movement　laws　of　creature,　but　also　has　its　shape.　In　order　to　simplify　the　design　process　and　improve　the　design　efficiency　of　one-degree-of-freedom　(DOF)　bio-inspired　mechanism　(especially　six-bar　or　eight-bar　mechanism),　a　design　method　based　on　layered　constraint　conditions　is　proposed　in　this　paper.　On　the　basis　of　the　one-DOF　kinematic　chain,　the　frame　is　selected　and　the　links　are　added　in　turn.　At　the　same　time,　the　constraint　conditions　are　given　in　layers　in　the　form　of　inequalities.　When　a　closed　loop　is　formed,　the　kinematic　model　needs　to　be　established,　and　the　positions　of　the　target　points　or　the　attitudes　of　the　target　links　can　be　represented　by　the　driving　angles　or　given　angles.　Thus,　the　feasible　configurations　and　the　ranges　of　the　link　lengths　can　be　obtained.　By　cycling　the　above　process,　the　target　points　can　approach　the　reference　points　quickly　and　the　design　efficiency　of　the　mechanism　can　be　improved.　The　effect　of　the　different　basic　kinematic　chain,　closed-loop　forms　and　constraint　conditions　on　configurations　and　design　efficiency　is　analyzed　in　detail.　It　provides　a　reference　for　the　design　of　other　one-DOF　mechanisms　with　multiple　constraint　conditions.