Gallium was intentionally used to catalyze the growth of brushhead-like and feather-like silica nanowires through thermal evaporation. Due to the different amount of Ga element deposited on the two silicon substrates, the growth of brushhead-like structures was catalyzed by Ga on one silicon substrate, while the feather-like structures were self-assembled on the other silicon substrate. Photoluminescence analysis shows that the brushhead-like structures have two emission peaks centered at 397 nm and 457 nm, and the feather-like structures have only one emission peak centered at 406 nm. The growth rate determined by the Ga catalyst of the brushhead-like and feather-like structures would affect the structure defects in the silica nanowires, which are responsible for their difference in optical properties.