a diacid monomer of benzobisoxazole 2, 6-di(p-phenylene-carboxylic) acid (bbodpa) was synthesized in a simple procedure, and characterized by means of ftir, 1h nmr and 13c nmr. the resulting bbodpa was polymerized with 3, 3'-diaminobenzidine tetrahydrochloride (dab) to prepare poly (bibenzimidazole-p-phenyl-benzobisoxazole) (pbbibbo) in polyphosphonc acid. the inherent viscosities values of pbbibbo indicated that it was a kind of high molecular weight polymer. the structure of pbbibbo was confirmed by 1h nmr, 13c nmr and ftir. thermal properties and dissolubility of pbbibbo were also investigated. these results showed that pbbibbo exhibited good thermal stability.