Patterned c-plane sapphire substrate is prepared by chemical etching. GaN films are grown by LP-MOCVD on surface treated sapphire substrate and common c-plane sapphire substrate. The structure and properties of the GaN films are analyzed by high-resolution double crystal X-ray diffraction(DCXRD), scanning electron microscope(SEM) and atomic force microscope(AFM).The results indicate that the quality of GaN film grown on sapphire substrate prepared by surface treatment is superior to that grown on common c-plane sapphire substrate. High-resolution double crystal X-ray diffraction shows that for the GaN grown on surface treated sapphire substrate,the (0002) and (1012) reflections have full-width at half-maximum as low as 208.80arcsec and 320.76 acrsec, respectively. The shortcomings of procedure complexity and high crystallographic tilt in conventional lateral epitaxial overgrowth are overcome by using the new method.