The　development　of　(K,　Na)NbO3　(KNN)-based　lead-free　materials　with　excellent　piezoelectric　properties　has　become　an　vital　aspects　in　recent　years,　based　on　the　environmental　friendliness　and　potential　for　device.　As　the　typical　electromechanical　property,　the　electrostrictive　effect　is　tightly　linked　to　piezoelectric　response,　which　is　dominating　the　market　of　high-precision　actuators.　However,　the　electrostriction　behaviors　of　KNN-based　piezoelectric　materials　have　been　little　studied　as　yet,　evoking　the　exploration　for　the　electrostrictive　effect　potential　urgently.　Here,　a　typical　KNN-based　piezoelectric　material　of　(1-x)K0.5Na0.5NbO3-xBi0.5Na0.5ZrO3　(KNN-xBNZ,　x　=　0.09,　0.10,　0.11)　has　been　concentrated　on　the　enhanced　relaxor　characteristic　due　to　destroyed　ferroelectric　long-range　orders　via　introducing　high　content　of　BNZ,　aiming　to　strengthen　the　electrostriction.　A　giant　electrostrictive　coefficient　(Q33　∼　0.067　m4/C2)　is　achieved　in　KNN-0.1BNZ　materials,　nearly　three　times　higher　than　that　of　reported　Pb(Zr,　Ti)O3-based　materials,　and　comparable　to　some　typical　BaTiO3-based　materials.　The　optimization　of　Q33　roots　in　the　co-doped　appropriate　of　Bi3+　and　Zr4+　at　A　or　B　site,　which　induces　the　heterogeneous　structure　and　then　limits　the　range　of　movement　for　ions　on　B　site.　Significantly,　a　pretty　frequency　stability　of　the　remarkable　Q33　(>0.054　m4/C2　under　the　frequency　of　1–100　Hz)　is　revealed,　benefiting　to　application　for　some　commercial　fuel　injectors’　actuators.　This　research　provides　a　high-performance　electrostrictive　material,　promoting　the　research　of　eco-friendly　piezoelectric　materials.　©　2022　Elsevier　Ltd　and　Techna　Group　S.r.l.