Abstract: La2O3 powder was prepared by sol-gel method with lanthanum nitrate，polyethylene glycol，and citric acid as raw materials，and the influences of dispersant species（polyethylene glycol and citric acid），calcination temperature，and calcina- tion time etc.on the grain size of La2O3 powder were investigated，and the performance of water absorption was also discussed. Results showed that the grain size of lanthanum oxide prepared with polyethylene glycol was less than that prepared with citric acid；dry gel can be completely decomposed into lanthanum oxide by calcined at 780 ℃ for 1 h；the higher calcination temperature and the longer calcination time，the larger grain size；lanthanum oxide will become La（OH）3 when it exposed to the air because of its strong water absorption.The study could be a reference for the controlling of powder grain size.

Key words: sol-gel method, La2O3, grain size, polyethylene glycol, citric acid