The synthesis of complexional ultrafine zinc oxide powders by controlled-release precipitation method, which is a precipitation process of precursor by controlling ammonia distillation rate in ammonia solution under the combination effect of microwave heating and ultrasonic cavitating, and followed by subsequent heat treatment was investigated. The characteristic of precursor and zinc oxide powders were studied using X-ray diffraction, scanning electron microscopy, TG-DTA-DTG, FT-IR, and ultraviolet-visible pectrophotometer. The coloring mechanism of complexional zinc oxide is discussed. This has shown that a tentative composition of the precursor is likely Zn3CO3(OH)4·H2O. Complexional zinc oxide particles of an average particle size of 200 nm with narrow size distribution, good dispersibility and hexagonal appearance could be obtained after annealing at 350°C for 1.5 hour. ZnO particles are complexional, probably due to nitrogen atom or N-H bond entering into crystal lattice of zinc oxide. Complexional zinc oxide has fine capacity of shielding UV and absorbing wide range of wavelength.