BaTiO3 (BTO) waveguide thin films were prepared by pulsed laser deposition (PLD) on single crystal MgO substrate. In order to improve the crystalline quality and surface roughness, two process parameters of growth temperature and laser energy were studied and optimized, and the film sample was conducted in-situ annealing. The crystallization effect of BTO thin film was found in the first direction. The dependent relations of quality characteristics and growth temperature were analyzed, and the effects of different laser energy on the crystalline film surface roughness were studied. The crystallization effect and characteristic of the film were characterized by X-ray diffraction. The surface morphology and roughness were detected by atomic force microscopy. The results indicate that BTO film could be c-axial oriented film. High strength sharp diffraction peak appeared in the direction of (001) and (002). The film has good crystal quality and small surface roughness of 0.563 nm.