The　analysis　and　comparison　of　the　different　traditional　dexterity　measures　of　manipulators　was　made,　and　a　new　dexterity　measure　was　presented.　Furthermore　the　sensitivity　of　the　measure　was　defined,　which　can　be　used　to　evaluate　the　stability　of　the　dexterity.　Based　on　these　measures,　the　kinematic　dexterity　of　planar　and　spatial　robots　was　studied.　Meanwhile　the　dexterity　of　the　optimization　results　in　different　dexterity　measures　are　compared.　From　the　results　obtained　it　can　be　observed　that　the　optimal　posture　determined　by　the　new　measure　is　more　dexterous.