A frequency octupling radio over fiber (ROF) system based on a dual-parallel Mach-Zehnder modulator (DPMZM) capable of overcoming the bit walk-off effect and realizing carrier reuse is proposed. A composite radio-frequency (RF) signal is used as the driving signal of the DPMZM at the central station (CS) to realize that the data is modulated on the +4th-order sideband only, and a pilot signal is inserted to realize the carrier reuse at the base station (BS). The operating principle of the designed system is theoretically analyzed and verified by simulation experiments. For the Q value is greater than 6, the transmission distance of fiber of the uplink and downlink of the system exceed 290 km and 80 km, respectively. The effect on the Q value when the main device parameters of the system deviate from the design value is analyzed. The innovation of this paper lies in the fact that the system not only overcomes the bit walk-off effect, but also solves the problems of degradation of the performance of the downlink and the poor system tunability caused by the conventional carrier reuse, and increases the transmission distances of fiber and the performance of the system considerably, and has important application prospect in ROF.