High-accuracy ranging system is of significance both in future space-based sciences and in large-scale manufacture. Based on the light intensity, a method of measuring absolute distance in a long range by using the optical frequency comb is demonstrated. The temporal coherence of the pulses emitted from the optical comb is analyzed. The measurement principle is introduced. The peak position of the interference fringe is analyzed, which can contribute to the distance measurement, and numerical simulations are also developed correspondingly. The experimental results show that the absolute distance measurement can be realized. This method can be used to measure a large-scale distance.