Barium strontium titanate (Ba0.7Sr0.3TiO3-BST) powder was prepared via a solid-state reaction method. The thick film ceramic with a thickness of approximately 55 μm was procured by a tape-casting approach. The crystalline structures and morphologies of the ceramic samples were analyzed by X-ray diffraction and scanning electron microscopy. The dielectric and ferroelectric properties of the BST ceramics were analyzed by a precision impedance analyzer and a ferroelectric polarization-electric field (P–E) hysteresis loop tester, respectively. The electrocaloric effect was calculated based on the Maxwell relations and the P–E loops, and the energy storage density and energy storage efficiency were calculated using the discharge part of the P–E loops. An adiabatic temperature is 3.43 K at the Curie temperature of 330 K (57 ℃) and the electric field of 30 MV/m and a discharge energy density is 1.43 J/cm3 at 30 MV/m for BST thick film ceramic, indicating a promising potential application for ECE and energy storage devices.