The　piezoelectric　effect　can　effectively　modulate　the　energy　band　structure　of　the　optoelectronic　semiconductor　and　the　transport　behavior　of　carriers.　Here,　we　propose　a　BaTiO3/SrTiO3　nanocomposite,　and　effectively　enhance　its　photocatalytic　performance　through　piezoelectric　effect.　The　heterostructured　BaTiO3/SrTiO3　nanofibers　were　prepared　by　electrospinning,　and　they　were　polarized　by　a　high-voltage　electric　field.　Under　the　co-excitation　of　ultrasonic　and　UV　irradiation,　the　BaTiO3/SrTiO3　nanofibers　presented　excellent　degradation　ability　of　pollutants　in　water.　The　BaTiO3/SrTiO3　nanofibers　can　degrade　Rhodamine　B　(RhB)　dye　by　similar　to　97.4%　within　30　min　under　the　combined　action　of　ultrasonic　and　ultraviolet　irradiation,　which　was　2.2　times　that　of　pure　SrTiO3　nanofibers.　The　piezoelectric　effect　provides　a　built-in　polarization　field　to　improve　the　separation　efficiency　of　photo-generated　carriers.　Moreover,　DFT　calculation　results　showed　that　piezoelectric　potential　can　reduce　the　band　gap　width　of　the　SrTiO3.　This　article　provides　a　promising　strategy　for　improving　photocatalytic　performance　of　nanocomposites　through　the　use　of　mechanical　energy.