Selective MOVPE growth of GaN microstructure on silicon substrates has been investigated using SiO2 mask having circular or stripe window. In case of (001)substrate, grooves with (1 1 1) facets at the sides were made by using the etching anisotropy of a KOH solution. On the (1 1 1) facets of patterned silicon substrate (or on the as opened window region of (1 1 1) substrate), growth of wurtzite GaN was performed, of which the c-axis is oriented along the (1 1 1) axis of silicon. The photoluminescence and X-ray diffraction analysis were performed to characterize the single crystal to reveal the effect of the growth conditions of the intermediated layer and the microstructure.