A two-step process for preparing glass fibers (GFs) reinforced beta-nucleated PP composites was designed and developed. The complementary approach combined GFs reinforcement and beta-nucleating agents regulation using N,N'-dicyclohexyl-2,6-napthalene-dicarboxamide (TMB-5) in the presence of maleic anhydride grafted polypropylene (PP-g-MA) through extrusion blending. The influence of TMB-5 and GFs on the mechanical properties and crystallization behavior of PP was studied by mechanical test, wide-angle Xray diffraction, differential scanning calorimetry, and scanning electron microscopy. A distinct complementary effect of GFs and beta-nucleating agent TMB-5 on mechanical properties and crystallization behavior of PP was observed. Results showed that addition of 20 wt % GFs and 0.1 wt % TMB-5 into PP matrix with the two-step process could lead to significant increase to its mechanical properties: specifically 64.8% improvement in tensile strength, 107.1% enhancement in flexural modulus, and 167.7% increasement in notched impact strength compared to that of neat PP. Furthermore, with the combination of TMB-5 and GFs, not only led to promoted interfacial adhesion, but also significantly improved overall comprehensive mechanical properties. The complementary process provided an alternative approach for the development of PP with balanced toughnesss and stiffness.