Abstract: BaSO₄ crystal particles were synthesized by using water-soluble polyethylene glycol 4000（PEG4000） as dispersant.The effects of factors，such as reaction method，PEG4000 concentration，and amount-of-substance of Ba²⁺ to SO₄^2- etc.，on the morphology and crystal structure of the products were researched and characterized by the ways of scanning electron microscopy（SEM），transmission electron microscopy（TEM），and X-ray diffraction（XRD）.The results showed that both the aging and reflowing process were favorable for the ‘dissolution and regrowth process’ of BaSO₄ particles and for getting larger BaSO₄ particles；the morphology of BaSO₄ crystal changed from the  cross flower shape sheet to rod-shaped particles with the increasing of concentration of PEG4000 and when at the right concentration，sheet-like single crystal structure with good glossy performance could be obtained；And the change of the amount-of-substance ratio of Ba²⁺ to SO₄^2- could also affect the morphology of BaSO₄ particles to get a novel nanostructure of ‘fish bone spurs’ shape.

Key words: BaSO₄, PEG, morphology