ZnO nano-powders was prepared on the surface of exfoliated kaolinite(with the precursor solution of(ZnAc2·2H2O) and ammonia) via microwave heating hydrolysis method,the nanocrystalline ZnO was(characterized) by using XRD,FTIR,TEM and their formation mechanism was proposed.The results indicate that the products are composed of hexagonal-phased ZnO.The morphology of ZnO is rod-like without exfoliated kaolinite(length is 100-200 nm,diameter is 50-80 nm) as well as is cluster whisker-like in the presence of exfoliated kaolinite(length is 200-350 nm,diameter is 40-60 nm).The infrared absorption of the latter was enhanced apparently.The formation mechanism of the nanocrystalline ZnO synthesized by this method was also suggested.