Abstract: A type of polyacrylonitrilebased carbon fiber (MPG) was co-modified with KH570-surface-treated graphene and acidified multi-walled carbon nanotubes (MWCNTs), and then the MPG/MWCNTs/graphene composites (MPG-P) was prepared by a wet-processing method. The resulting MPG was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. Furthermore, the electrical conduction, mechanical properties, pore size distribution and porosity of MPG-P were investigated by four-probe tester, universal testing machine and porous material analyzer. The results indicated that the composites achieved the optimum tensile strength of 37.21 MPa when 0.2 wt% of MWCNTs and graphene was incorporated, and their electrical resistivity and porosity reached 13.17 mΩ·cm and 63.7 %, respectively. The tensile strength reached an optimum value of 44.95 MPa at an MWCNTs/graphene mass ratio of 1∶2, which increased by 48.94 % compared to pristine carbon fiberbased composite. At this mass ratio, the resistivity and porosity also reached 13.52 mΩ·cm and 62.57 %, respectively.