In order to be compatible with the existing optical communication network, a time delay fluctuations measurement based on "single-fiber one-way" transfer scheme was proposed. Based on the temperature-induced variation of group velocity dispersion effect and Sellmeier equation, a proportionality model for calculating the one-way delay fluctuations was established with detecting the delay difference fluctuations between two propagating optical signals at given different wavelengths and accurate temperature measurement. Assuming proportionality coefficient in the model was the ratio between one-way delay fluctuations and one-way dual wavelength delay difference fluctuations. By simulation, the impact of fiber link parameters, such as temperature and wavelength difference, on proportionality coefficient was discussed. The experimental platform for one-way time transfer over 75 km fiber was conducted and the experimental results show that the measured proportional coefficient is -258.4, close to the theoretical proportional coefficient -277.3, and the corresponding one-way delay variation error is 660 ps. The measured results validate the correctness of the proposed model as well as the possibility of fiber time delay fluctuations measurement based on one-way transfer.