Abstract: Poly(2,5-benzoxazole) (ABPBO) was synthesized from 3-amino-4-hydroxybenzoic acid hydrochloride made by solution polycondensation in the solvent of polyphosphoric acid (PPA). Chemical structure of the polymer was tested with ATR-IR. Then the dynamic rheological behavior of ABPBOPPA solution was tested with a parallelplate rheometer, and the steady flow curve was tested with a capillary rheometer. Results showed that the storage and loss modulus increased as frequency increased, and storage modulus increased more quickly than the loss modulus. ABPBO-PPA solution tended to Newtonian fluid with the temperature rising. However, it tended to nonNewtonian fluid with the increasing of the ABPBO-PPA concentration. ABPBO-PPA solution behaved sharp pseudoplastic. And the disparity of viscosities with different temperatures decreased with the shear stress increasing.