Cable-driven　parallel　manipulator　(CDPM)　has　the　characteristics　of　simple　structure,　light　weight,　large　workspace　and　strong　carrying　capacity,　so　it　is　applied　to　many　fields.　In　this　paper,　we　proposed　the　tension　distribution　index　(TDI)　to　evaluate　the　tension　distribution　performance　of　the　CDPMs　and　improved　the　original　stiffness　index　(SI)　considering　the　influence　of　cable　tension.　Comprehensively　considering　TDI,　SI　and　dexterity　index　(DI),　the　global　quality　workspace　(GQWS)　is　proposed.　A　redundantly　constrained　6-Dof　CDPM　is　studied　in　this　paper　as　an　example.　We　optimized　the　geometrical　parameters　of　the　CDPM　with　the　goal　of　maximizing　the　global　quality　workspace　(GQWS).　The　simulation　results　show　that　the　optimized　CDPM　has　better　performance　than　before,　which　demonstrate　that　the　evaluation　approach　proposed　in　this　paper　is　of　effectiveness　and　value　for　the　design　and　analysis　of　CDPMs.　This　approach　can　also　be　used　in　other　kinds　of　CDPMs.