The epitaxial growth features of YBa₂Cu₃O_(7-x) (YBCO) films on (100) SrTiO₃ substrates have been studied by Rutherford backscattering spectrometry and axial channeling technique. A typical minimum yield value, X_min, of Ba yielded in channeling spectrum is 4.6 % for the film of 166 nm. Only (00L) peaks appeared in X ray diffraction patterns of the films. The results indicate that the YBCO films have good epitaxial growth quality with c- axis orientation perpendicular to the substrate surface. Simulation of RB process in films and substrates have also been performed using RUMP program, and analysis shows that compositions of the films are uniform with near (123) stoichiometry. The higher interface yields in the aligned spectrum reveal that there are extra defects in the interface layer owing to lattice mismatch and interface interaction.