In view of the lack of considering the temperature component in the statistical analysis of the horizontal displacement of the concrete faced rockfill dam (CFRD), the water pressure component is derived from the Boussinesq solution and it has been proved that the horizontal displacement in the typical section of the dam is directly proportional to the reservoir water level. The expression of the aging component is derived based on the Merchant rheological model, the aging relationship of the periodic non-monotonic increase of rock fill is established and the temperature component is added by the form of measured temperature. Thereafter, a modified hydrostatic thermal time (MHTT) model is proposed as the statistical model of internal horizontal displacement of CFRDs. The results of a case study show that the MHTT model has not only a better data interpretation ability than the HTT model and HT-JU model, but also a strong ability to interpret the physical mechanism of horizontal displacement of CFRDs.