Nanosized ceramic powder was prepared by laser ablation under different atmospheres using a ceramic target composed of ZrO 2, TiO 2, ZnO and Al 2O 3. Physical characteristics and microstructure of nanoparticles, including particle morphology, phase transformation, powder compositions and far-infrared emissivity, have been investigated. The laser-ablated nanoparticles exhibit two kinds of particle size distribution with 7-15 (70-90%) and 40-100 nm (10-30%). Nanoparticles synthesized at lower laser fluences show poor crystallinity but rich Zn composition. While increasing laser fluence, better crystalline nanoparticles with rich Zr composition were obtained. It was found that both composition and morphology of nanoparticles change with laser fluence. The average far-infrared emissivity of the nanoparticles varies with crystallinity of nanoparticles.