TEA CO₂ laser beam was used to irradiate the mixed crystal of NiSO₄ and Ni(Ac) ₂ , which had been grained into powders of 2μm size and then pressed into pieces of 10 mm diameter as target material. Nanoparticles of NiSO₄/Ni(Ac)₂ , containing a little Ni₂O₃ , were prepared. The size of which was 10 to 20 nm. And the gas products were H 2O and CH 3COOH. The laser power density was of 10⁸ W.cm^-2 order of magnitude. The mechanism of laser action is discussed. A method of laser ablation for preparing nanoparticles, the chemical composition of which is as similar to that of the target material as possible, is being offered.