1 μ m-thick YBa 2 Cu 3 O 7 - δ (YBCO) films were grown on the Y ₂ O ₃ /yttria stabilized zirconia (YSZ)/CeO ₂ buffer layers with different surface morphologies using direct-current sputtering. The critical current density ( J c ) value of YBCO was 1.1 MA/cm ² when the root mean square surface roughness ( R rms ) of the buffer layer was 2.5 nm. As the R rms of the buffer layer increased to 15 nm, the J c decreased to 0.3 MA/cm ² . X-ray diffraction and scanning electron microscopy showed the strong relevance of the evolution of the structure and surface morphologies of YBCO films with the buffer layer of different R rms . A model was proposed to explain the influence of surface morphology on the superconducting properties of YBCO films.