Abstract: Adopting KOH solution anisotropy etching method, we obtained grooves with side facets on a Si substrate by studying the effects of isopropyl alcohol (IPA) and ultrasonic agitation on the etching. Based on this, we achieved the lateral epitaxial growth of GaN on planes of Si patterned substrate. The Bragg angle of GaN measured by double crystal X-ray diffraction (DCXRD) is 18.45,which indicates that we have grown semi-polar GaN on Si patterned substrate. The value of full-width at half-maximum (FWHM) of GaN layer is 1556 Arc sec.