The　occupation　behavior　of　Y2O3　in　nonreducible　BaTiO3-based　ceramics　was　investigated　thoroughly.　Based　on　XRD,　SEM,　TEM-EDS,　and　complex　impedance　analysis,　it　is　ensured　that　there　exists　two　turning　points　of　Y2O3,　0.50　mol%　and　1.00　mol%,　and　the　latter　is　the　solubility　limit.　Below　0.50　mol%,　the　introduced　Y3+　ions　precede　to　enter　the　A　sites　of　the　perovskite　lattice,　causing　an　observed　enhancement　in　dielectric　constant　and　energy　storage　density　accompanied　by　an　increase　in　grain　size.　Once　the　addition　exceeds　0.50　mol%,　the　Y3+　ions　will　turn　to　occupy　B　sites　to　substitute　for　Ti4+　ions,　leading　to　the　significant　reduction　in　dielectric　constant　and　energy　storage　density.　Above　the　solubility　limit　of　1.00　mol%,　the　excess　Y3+　ions　would　segregate　at　grain　boundary　and　even　induce　the　formation　of　Y2Ti2O7　phase,　resulting　in　an　abrupt　enhancement　of　grain-boundary　resistance.　Doped　with　0.75-1.50　mol%　Y2O3,　all　nonreducible　specimens　meet　X7R　requirement.