The novel poly(hydroxy-p-phenylenebenzobisoxazole) (HPBO) was synthesized by different polymerization routes, including hydroxy-orderly distributed polymer (ord-HPBO) and hydroxy-randomly distributed polymer (ran-HPBO). Surface elemental composition, thermal stability, intrinsic viscosity, UV resistance, surface morphology, mechanical and interfacial properties of HPBO fiber were investigated. ATR-FTIR and EDS spectrums identify the formation of mono-hydroxyl modified polymer. Excellent thermal stability (up to 600 degrees C), mechanical properties (tensile strength of 4.32 GPa, modulus of 169.7 GPa) and rheological spinnability of ran-HPBO-AS via HD self-polymerization route were obtained. Meanwhile, the SEM after UV irradiation indicated that the photostability of HPBO is better than PBO. The interfacial shear strength (IFSS) between HPBO-AS fiber and epoxy resin is 21.7 MPa, 87.1% higher than that of PBO-AS fiber. Comparing different HPBO synthesis routes, the self-polymerization of HD salt route is believed to be a feasible route for industrial production and the ran-HPBO is expected to become a new generation of high-performance fiber. (C) 2018 Elsevier Ltd. All rights reserved.