By considering the temperature-induced variation in the refractive index of optical fiber, a theoretical model of the proportion consistency between time delay variations and single-wavelength signal and time delay difference variations of dual-wavelength signals in one-way and round-trip dual-fiber links was obtained. Furthermore, a dual-fiber one-way time transfer method compatible with the existing optical communication network was proposed. The time delay difference variations of dual-wavelength and proportion with wavelength and temperature were investigated via simulation. The experiment for one-way time delay measurement using 75-km dual-fiber link was conducted to investigate the proportion consistency model. Results show that the measured proportion at the remote site after 50-km transmission is -266.9 and that after transmission back to the local site using 75-km round-trip dual-fiber link is -256.4. The difference between theoretical and practical values of the one-way time delay variation is 520 ps. The simulated and measured results validate the feasibility of the proposed one-way time transfer method based on a dual-fiber link.