High-performance　lead-free　piezoelectric　materials　have　become　a　hot　topic　in　the　field　of　advanced　functional　materials.　In　2009,　the　(1　-x)Ba(Zr0.2Ti0.8)O-3-x(Ba0.7Ca0.3)TiO3(BZT-BCT)　system　with　surprisingly　high　piezoelectric　properties　was　first　proposed　by　Liu　and　Ren;　as　a　milestone　discovery　in　the　field　of　ferroelectrics,　it　has　aroused　extensive　attention.　In　this　review,　initially,　we　highlight　the　remarkable　electrical　properties　of　the　BZT-BCT　system,　and　then　summarize　the　advances　in　the　BZT-BCT　material　based　on　five　aspects　including　the　origin　of　its　high　properties,　preparation　and　poling,　grain　size　control,　chemical　modification　and　texture　design.　We　focus　on　a　systematic　discussion　of　its　phase　boundaries,　domain　structure,　and　defect　chemistry　in　relation　to　improved　dielectric　and　piezoelectric　properties.　In　addition,　the　device　performance　of　BZT-BCT　materials　is　also　evaluated.　Due　to　their　excellent　comprehensive　properties,　BZT-BCT　materials　have　been　widely　studied　in　various　applications　such　as　energy　harvesters,　flexible　sensors　and　energy　storage　capacitors.　Finally,　based　on　the　state-of-the-art　knowledge,　we　present　an　outlook　on　the　challenges　and　application　prospects　of　BZT-BCT　materials.　This　review　will　help　promote　the　practical　applications　of　BZT-BCT　materials,　and　accelerate　the　development　of　lead-free　ferroelectric　materials　in　specific　fields.