Based on the rapid freeze-thaw test and tensile test, the effects of four freeze-thaw media on the mechanical properties of basalt fiber (BF) unidirectional sheet in freeze-thaw environment were studied, and the corresponding tensile strength damage model in freeze-thaw environment was proposed. The results show that salt freezing will lead to the shedding of the wetting agent film and the degradation of basalt fiber. The erosion effect of basalt fiber is the most significant when the freeze-thaw medium is 3.5wt % NaCl + 3.0wt % Na2SO4. The failure modes of tensile standard specimens can be summarized as four types: middle centralized failure, middle decentralized failure, end centralized failure and end decentralized failure. The tensile strength and ultimate elongation of the specimens decreased the most under the freezing and thawing medium of 3.5 wt% NaCl + 3.0 wt% Na2SO4. The effect of salt freezing on the elas-tic modulus of the specimens was not significant. The proposed tensile strength damage model under freeze-thaw environment is in good agreement with the experimental results. This study can provide theoretical support for the durability design of existing structures reinforced by BF unidirectional sheet in salt freezing environment.