The　evolution　of　electrical　properties　with　an　electric　field　(E)　was　compared　between　single-phase　BT　ceramic　and　phase-coexistence　BT-based　(BTS-0.15BCT)　ceramic.　The　dielectric,　ferroelectric,　piezoelectric,　and　strain　properties　are　all　found　to　be　electric　field-dependent,　especially　for　BTS-0.15BCT　ceramic　with　small　domains　and　easy　polarization　rotation　induced　by　phase　coexistence.　High　ferroelectric　and　strain　properties　are　obtained　in　this　ceramic　because　sufficient　domain　switching　can　easily　be　achieved.　The　high　dielectric　constant　can　be　further　elevated　after　poling　this　ceramic　due　to　the　E-induced　multiphase　transitions.　Dynamic　piezoelectric　measurement　reveals　that　the　dynamic　piezoelectricity　can　reach　to　similar　to　740　pC/N,　which　is　much　higher　than　the　static　value　(similar　to　620　pC/N)　of　poled　BTS-0.15BCT　ceramic.　However,　the　converse　piezoelectric　coefficient　will　decrease　at　high　E,　because　of　the　quick　decrease　in　dynamic　dielectric　response　caused　by　clamped　polarization　at　high　E.　All　the　results　demonstrate　that　phase-coexistence　BT-based　ceramic　shows　electric　field-related　properties　due　to　the　soft　structure,　whereas　it　cannot　be　observed　in　BT　ceramic　with　stable　phase　structure　and　large　domains.　This　work　reveals　the　evolution　difference　and　structure　origin　of　electrical　properties　in　BT-based　piezoceramics　with　different　phase　structures.