Epitaxial YBCO films were deposited on (100) LaA1O3 single-crystal substrates by metalorganic deposition of metal trifluoroacetate precursors with different concentrations. All the YBCO films have Tc around 91 K and Jc excess 2MA/cm2 at 77 K in zero field. XRD θ-2θscans show all the films have c-axis normal orientation. The FWHM (full width at half-maximum intensity) values of X-ray ω-scans of (005) reflection are 0.379°, 0.283°, and 0.543° for the YBCO thin films deposited with precursor solution concentrations of 1.52, 1.0, and 0.75 mol/L, respectively. With the concentration of the precursors decreasing, the thickness of the films decreases linearly. SEM micrographs show that porosities in the films become bigger with the precursor solution concentration decreasing. The big porosities in the film with the lowest concentration precursor deteriorate the superconducting property and make it have a wider superconducting transition and a lower Jc.