A laser ranging of dual-sweep frequency scanning interferometry system based on double-sideband modulation was demonstrated. The electro-optic double-sideband modulation was used to create dual swept signals with opposite scanning directions. For each receiving terminal, the beat frequency signal related to relative distance was obtained. By multiplying both beat signals, measurement errors caused by disturbances in the optical path could be greatly reduced. The system was simulated in Optisystem. The simulation results indicate that the variations in the optical path length are eliminated efficiently. In addition, an experimental structure was proposed with vibrations in the optical path length. The experimental results show that the vibrations are suppressed for over 14 dB, which indicates that the precision can be improved effectively.