This work focuses on the study of mechanical and structural properties of glass fiber‐reinforced polypropylene (PPGF) composites compatiblized with maleic anhydride (MAH) grafted PP (PP‐g‐MAH). Thus, effects of the compatibilizer on the flow capacity, fiber orientation and length distribution, thermal and mechanical properties were evaluated. Combining fiber length and melt flow index (MFI) results, it can be speculated that when the compatibilizer is added, the level of fiber matrix interaction increases and the fluidity of the molten composite material improves, resulting in a better orientation and a lower level of fiber length degradation. Moreover, the mechanical analysis based on the micromechanical model was conducted to estimate the effect of the compatibilizer on the interfacial shear stress, orientation factor, and the tensile strength. The main results indicate that the experimental data have confirmed the validity of the micromechanical model. POLYM. COMPOS., 39:3497–3508, 2018. © 2017 Society of Plastics Engineers