<p>Existing models for the freeze-thaw damage of concrete consist mainly of discrete prediction models based on freeze-thaw test data from saturated or highly saturated concrete. These models have difficulty reflecting how temperature and saturation would affect hydraulic concrete’s performance loss from freeze-thaw cycles. To address this problem, this study first improved a formula of equivalent damage age to reflect the effects of freeze-thaw temperature and saturation. Next, the fractional-order freeze-thaw damage model of hydraulic concrete for sealed freeze-thaw and water-freeze-thaw concrete was established by using fractional calculus theory. Finally, freeze-thaw tests of hydraulic concrete under three freeze-thaw temperatures and three saturation conditions were designed and carried out. The loss rates of strength obtained by tests served as input to the GWO algorithm to predict the freeze-thaw damage of hydraulic concrete based on the freeze-thaw temperature and saturation, and the model’s applicability was verified. The results show that the loss rates of strength increase with increasing equivalent damage age. In addition, the loss rate of both types of strengths increases with decreasing freeze-thaw cycle temperature and increasing saturation, and the loss rate of splitting tensile strength exceeds the loss rate of compressive strength for a given freeze-thaw temperature and saturation level. The correlation coefficients between the fitted values and the test values of the sealed and water freeze-thaw concrete specimens are 0.950–0.958 and 0.903–0.924, respectively, which indicates that the fractional-order freeze-thaw damage model developed in this paper is reliable.</p>