Based　on　the　configuration　synthesis　and　optimum　principles　of　exoskeleton　mechanism,　PPRRRP　and　RRRPU　exoskeleton　configurations　are　proposed.　In　preferred　configurations,　the　two　human-machine　closed　chains　which　both　consist　of　the　exoskeleton　mechanism　and　the　human　upper　limb　are　translated　into　an　3-DOF　(degree　of　freedom)　exact　kinematic　constraints　system　by　introducing　passive　joints　at　the　connection　position　of　the　human　and　the　exoskeleton,　in　order　to　realize　kinematic　compatibility.　From　the　perspective　of　the　whole　human-machine　closed　chain,　the　kinematics　models　of　the　human-machine　closed　chains　of　PPRRRP　and　RRRPU　are　established.　Through　the　reasonable　decomposition　and　kinematic　characteristics　analysis　of　passive　joints,　the　equations　of　kinematic　constraint　are　deduced,　and　the　velocity　Jacobian　matrices　of　the　two　human-machine　closed　chains　are　derived,　and　the　complexities　of　the　human-machine　closed　kinematic　chains　are　reduced　by　this　algorithm.　Through　the　numerical　simulation　of　velocity　Jacobian　matrices,　reciprocal　of　condition　number,　manipulability　ellipsoid　and　dexterous　operating　velocity　of　the　two　mechanisms　mentioned　above　are　analyzed　and　compared　in　the　coronal　plane,　sagittal　plane　and　horizontal　plane.　The　results　show　that　the　dexterity,　isotropy　and　dexterity　of　operating　velocity　of　the　PPRRRP　mechanism　are　better　than　those　of　the　RRRPU　in　the　above　three　planes.　On　this　basis,　an　upper　limb　rehabilitation　exoskeleton　of　PPRRRP　is　designed.　©　2018,　Science　Press.　All　right　reserved.