The　stability　of　the　tribological　properties　of　polymer　coatings　is　vital　to　ensure　their　long　term　use.　The　superlubricity　of　the　poly(vinylphosphonic　acid)　(PVPA)-modified　Ti6Al4V/polytetrafluoroethylene　(PTFE)　interface　can　be　obtained　when　lubricated　by　phosphate-buffered　saline　(PBS,　pH　=　7.2),　but　not　when　lubricated　by　deionized　water　and　ethanol.　Therefore,　the　mechanisms　for　the　superlubricity　of　PVPA　coatings　affected　by　lubricant　were　investigated　in　detail.　The　stability　of　the　PVPA　coatings　and　their　compatibility　with　the　lubricant　are　critical　factors　in　realizing　ideal　tribological　properties　of　PVPA　coatings.　Robust　PVPA　coatings　are　stable　under　a　wide　range　of　pH　values　(6-10)　using　PBS　as　the　basic　solution,　and　are　also　characterized　by　superlubricity.　The　hydrolysis　kinetics　of　phosphate　anhydride　is　the　main　reason　for　the　pH　responses.　In　addition,　along　with　stability,　PVPA　coatings　exhibit　different　friction　coefficients　in　salt　solutions　which　are　composed　of　various　ions,　which　indicates　that　the　compatibility　between　PVPA　coatings　and　the　lubricant　can　be　used　to　regulate　the　superlubricity　properties.　Based　on　a　fundamental　understanding　of　the　mechanism　of　surperlubricity　by　considering　the　effects　of　the　lubricant,　PVPA　coatings　with　stability　and　perfect　tribological　performance　are　expected　to　be　applied　in　more　aspects.