BaCO3 were synthesized using phthalic acid (PA) and isophthalic acid (IPA) as morphology adjust control agent, respectively. The BaCO3 powders were thoroughly characterized by XRD, and FT-IR spectroscopy. The morphologies of BaCO3 crystals were investigated by scanning electron microscope (SEM). The morphologies of BaCO3 crystals change from rod-shaped, shuttle-shaped to wireshaped with the increase amount of PA. While IPA was used as adjuster, the morphologies of BaCO3 crystals change from irregular block-like, flower-like to a mixture of irregular spherical-like and block-like particles with the increase amount of IPA. The result indicates that the morphology of BaCO3 may be adjusted by the structure of carboxylic acid.