ZrB2 powder has been prepared through carbothermal reduction boronization of zirconia/boron carbide/carbon mixtures heating assisted by microwave. The powder characteristics were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), nitrogen absorption (BET model) and scanning electron microscope (SEM). The experiments indicated that excessive B4C is necessary and the carbothermic reaction reacts severely at a higher temperature and complete at 1600oC. The crystallite size has ranged from 50-100 nm, according to the calculated surface area. Highest purity of ZrB2 powder, which was synthesized at 1600oC, is 99.67 wt%. The surface area of ZrB2 powder synthesis at 1600oC is 18.33 m2/g. Vibration of temperature should affect the purity of ZrB2, as the sub reaction acted.