Microelements in indium tin oxide(ITO) powders have a great impact on spectrum characteristics such as transmittance of film products. Seven microelements in ITO powders were determined by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). ITO powders were placed in a silver crucible with sodium hydroxide bedding and coverage, and melted by alkali at high temperature. The melt was leached and transferred into the solution with hot water and dilute hydrochloric acid. Matrix interference and spectrum interference between elements were eliminated by choosing the right working conditions. The precision, the detection line and the recovery rate of each element were studied, the results show that the precision of ICP-OES was no more than 1.2%, the recovery rate ranged from 98% to 104%. The results of multiple microelements in ITO sample agreed with the recommend value.