An important correlation of 1223 phase development to film thickness has been found on the films made by laser ablation and post-annealing on (100) LaAlO 3 single crystal substrate. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the 1223 phase development, epitaxy, and microstructure. When the film was thinner than 0.7 μm 1212 was the dominating phase, whereas when the film was thicker than 0.9 μm 1223 was the dominating phase without any change of the mean composition measured by energy dispersive spectroscopy (EDS). Resistance versus temperature and critical current density (J c ) were measured by the standard four-probe method. The zero-resistance transition temperature (T c ) was 72.4 K for the as-made pure 1212 film, whereas it was typically 105-111 K for the almost pure 1223 films depending on the 1223 phase purity. The typical J c value at 77 K and zero field was 2 10 6 A/cm 2 for the 1223 films.