Niu, X, Han, P, Tang, Z, Huang, J, Li, L, He, H, Zhang, W, Zhao, L, and Zhao, L. Cold stress induced a higher level of fat oxidation in women. J Strength Cond Res XX(X): 000–000, 2021—To investigate women's fat oxidation under cold stress during incremental exercise testing and compare the effect of cold stress on fat oxidation between the sexes. Twenty-six healthy subjects performed 2 incremental exercise tests to determine maximal oxygen uptake (V[Combining Dot Above]O2max) on a treadmill in different ambient temperatures. Cardiopulmonary variables were continuously recorded during incremental exercise tests. Maximal fat oxidation (MFO) and the corresponding exercise intensity (Fatmax) were determined from the fat oxidation curve constructed by indirect calorimetry. Both men and women relied more on fat oxidation in cold environment (p < 0.05). Compared with men, fat oxidation was significantly greater in women in the cold environment from 50 to 70% V[Combining Dot Above]O2max (p < 0.05). There were no significant differences in the change of fat oxidation as exercise intensity increased between the sexes (p > 0.05). Women had a greater MFO (p < 0.05) and Fatmax (p < 0.05) than men in the cold environment. When MFO was the dependent variable, sex, fat-free mass, fat mass, V[Combining Dot Above]O2max, and temperature accounted for 48% of its variability. We conclude that cold stress enhances fat oxidation in women. Compared with men, women have significantly higher value and rely more on fat oxidation to supply energy in the cold environment, although the increasing level of fat oxidation was similar between the sexes. These factors may have important implications in the individualization of exercise prescription in cold conditions for both men and women.