: A method involving secondary electrostatic flocking was used to prepare a ver-tically aligned array of pitch-based carbon fibers. The effects of the improved electrostatic flocking method on the density, perpendicularity, thermal conductivity, and heat trans-fer of the thermally conductive materials filled with pitch-based carbon fiber arrays were studied. The results show that pitch-based carbon fibers prepared with secondary flocking exhibited a significantly improved density and vertical alignment compared with those prepared with one-time flocking under the same flocking time. Additionally, when the film was contracted by 33%, the thermal interface material achieved a high vertical thermal conductivity of 27.4 W/(m·K). The material exhibited a good vertical thermal conductivity, and the preparation process shows great promise for industrial scalability and potential applications in the field of electronic chip heat dissipation.