Poly(vinylphosphonic　acid)　(PVPA)　cross　linked　networks　on　Ti(6)A(14)V　show　superlubricity　behavior　when　sliding　against　polytetrafluoroethylene　in　water-based　lubricants.　The　superlubricity　can　occur　but　only　with　the　existence　of　salt　ions　in　the　polymer　cross-linked　networks.　This　is　different　from　the　phenomenon　in　most　polymer　brushes.　An　investigation　into　the　mechanism　revealed　that　cations　and　anions　in　the　lubricants　worked　together　to　yield　the　superlubricity　even　under　harsh　conditions.　It　is　proposed　that　the　preferential　interactions　of　cations　with　PVPA　molecules　rather　than　water　molecules　are　the　main　reason　for　the　superlubricity　in　water-based　lubricants.　The　interaction　of　anions　with　water　molecules　regulates　the　properties　of　the　tribological　interfaces,　which　influences　the　magnitude　of　the　friction　coefficient.　Owing　to　the　novel　cross-linked　networks　and　the　interactions　between　cations　and　polymer　molecules,　their　superlubricity　can　be　maintained　even　at　a　high　salt　ion　concentration　of　S　M.　These　excellent　properties　make　PVPA-modified　Ti(6)A(14)V　a　potential　candidate　for　application　in　artificial　implants.