As one of the components of vanadium batteries, the low conductivity of bipolar plates has become an important factor in restricting the improvement of battery performance. Polyethylene (PE) and various dimensional conductive fillers, such as spherical carbon black (CB), flake graphite (FG), linear carbon fiber (CF), and carbon nanotubes (CNTW), were used as the main raw materials to prepare a point-line-surface three-dimensional highly conductive network carbon plastic composite bipolar plate, and the conductive mechanism was analyzed. The results show that 33% CB can form a conductive path inside PE. The addition of 15% FG increases the contact area with carbon black, thereby enhancing the electrical conductivity of the carbon plastic composite bipolar plate. The addition of 7% CNTW and 5% CF in the bipolar plate forms short-range and long-range conductive pathways, resulting in optimal electrical conductivity and bending strength of 20 S/cm and 46.5 MPa, respectively. The energy efficiency of the bipolar plate reaches 70% at a high current density of 300 mA/cm², which is 6.5% higher than that of the CB/FG bipolar plate. The energy efficiency of the bipolar plate does not decrease significantly after 500 charge and discharge cycles, indicating that the bipolar plate has good rate capability and service life.