The growth of In2 O3 nanowires on Si substrate with different zinc doping levels has been achieved by a vapor transport and condensation method. The atomic percentage in doping level is approximately proportional to the weight of ZnO powder added in the source. The ultraviolet (UV) and green light photoemissions of the In2 O3 nanowires are depressed and enhanced, respectively, with the doping level of Zn impurity. The UV and green light peaks are attributed to oxygen vacancy and zinc impurity energy levels. Similar tuning by other impurities can be expected and will be beneficial for possible optoelectronic applications.