In order to achieve high-precision distance measurement, this paper proposed a distance measurement method using linear sweep of AOM acousto-optic modulator. Based on the interference theory, a mathematical theoretical model between ranging distance, phase and frequency was established. In the ranging experiment, using the AOM acousto-optic modulator dual-pass frequency sweeping scheme, a ranging optical path experiment system was built to generate dual-frequency component light. Through the photodetector, the optical signal in the experiment was converted into an electrical signal. Because the non-optical interference signal was generated, the relevant electronic devices are added in the experiment to perform signal demodulation processing. Finally, the experimental data was processed by FFT transform, and the results show that the ranging distance is 24.17 m and the ranging fluctuation range is ±0.22 m.