Abstract: Nano[WT5.25BZ][JX-*6][KG-*2/3]-[KG-*3][JX*6][WT5”BZ]sized barium metaborate（β-BaB2O4） powder was synthesized by ultrasonic method with Ba(OH)2?8H2O and boric acid (H3BO3) as raw materials.H2O2 and surfactant PEG-400 had been added into the reaction system and the ultrasonic method was adopted,soft and hard agglomerates of particles were avoided simultaneously.FT-IR analysis showed that the initial product was BaB2O4?H2O2.TG-DTA-DTG analysis results showed that BaB2O4?H2O2 was decomposed at about 553 ℃,losing crystallization of hydrogen peroxide.XRD analysis results showed that β-BaB2O4 belonged to the space group of R3c(161) and C2/c(15).TEM photograph results showed that the particles were uniformly in shape and dispersed well with average size less than 70 nm in diameters.A preliminary discussion on the influences of function of H2O2,dropping rate,conversion temperature of amorphous into crystalline state,ultrasonic wave,and surfactant was also made. 

Key words: barium metaborate, ultrasonic method, nano[WT5.25BZ][JX-*6][KG-*2/3]-[KG-*3][JX*6][WT5", BZ]sized powder