The morphology of YBa2CusOr high-T, superconducting thin films grown on LaAIO3 substrates by pulsed laser deposition method have been studied by high resolution x-ray scattering and scanning electron microscopy. The results demonstrated that the thin films are almost complete c-oriented crystallised and twin in a-b plane, which is due to the orthorhombic structure. However, there are some a/b-oriented grains in the surface region of the thicker films. The interfacial strain were found in both the thin films and the substrates. The strain in the films, which is due to the lattice mismatch between the film and substrate, increases the dislocation density and makes the surface-parallel coherent length shorter. In the other hand, the strain in the substrates, which due to the mechanical polishing prior the growth. induces the inhomogeneous distortion on the substrates.