Piezoelectric　energy　harvesting　is　an　attractive　technology　for　recycling　energy　from　ambient　vibrations.　Many　big　challenges　still　limit　applications　for　the　piezoelectric　energy　harvester,　including　its　low-power　density　and　high　operating　frequency.　Although　many　studies　have　been　done　on　this　topic,　discussion　continues.　In　this　work,　a　modified　piezoelectric　cantilever　energy　harvester　(PCEH)　fabricated　with　(Ba0.85Ca0.15)(Ti0.9Zr0.1)O-3　ceramic　was　developed　with　a　low　operating　frequency　(20-40Hz)　and　a　high-power　density　(1.5-2.0W/mm(3)).　This　ceramic　presents　a　novel　rhombohedral-orthorhombic-tetragonal　multiphase　coexistence,　which　is　the　origination　of　the　enhanced　piezoelectric　response.　A　simple　method　is　provided　through　optimizing　the　number　of　proof　masses,　which　can　be　used　to　regulate　the　operating　frequency　of　piezoelectric　energy　harvester.　This　discovery　will　be　helpful　in　developing　new　piezoelectric　energy　harvesters　with　high-power　density　and　low　operating　frequency.