Nanocrystalline La2O3 were prepared by homogeneous precipitation method using urea as precipitant and La(NO3)3·6H2O as raw materials. The influences of various processing parameters in preparation process on the yield and mean size of the products were investigated. The optimum conditions for preparing nanocrystalline La2O3 are as follows: the molar ratio of urea to lanthanum nitrate hexahydrate is 6:1, the temperature of precipitation reaction is 115°C, the reaction time is 2.0 h, and the calcination temperature is 750°C. FT-IR, XRD and SEM were used to characterize the crystall...