Fe2(MoO4)3 ultrafine particle catalyst has been prepared successfully by the sol-gel process at lower temperature. The influences of preparation conditions and thermal treatment conditions on the morphology and structure of the ultrafine particle catalyst has been studied by using TEM, DTA-TG, FT-IR, XRD and BET surface area measurement methods. It is shown that the BET surface area of Fe2(MoO4)3 ultrafine particle prepared by sol-gel method is much larger than that of Fe2(MoO4)3 prepared by coprecipitation...