Abstract: Nano-crystalline yttria stabilized zirconia （YSZ） particles were synthesized by auto-ignited combustion. The influence of citrate to nitrate（c/n） molar ratio on the reaction products and the nano-crystalline grain size were investigated. Di-ester phosphate （PE） as a dispersant was added to the nitrate solution. The influence of PE dispersant in the precursor solutions on the resulted particles and its reaction mechanism were also investigated. The best molar fuel-oxidant molar ratio is 0.56 in the experiment and the nanocrystalline grains sized of 12nm are obtained. PE with the weight of 2wt% ZrOCl₂ is proved to be the best concentration from which typical nanoparticles sized of 30-70nm are obtained.