To study the quantitative influence and action mechanism of structural size and fiber volume fraction on the splitting tensile strength of basalt fiber reinforced concrete (BFRC) at extreme low temperature, four sizes (side lengths of 0,0, 150, and 200 mm) and four fiber volume fractions (fraction range of 0%~0.5%) of BFRC cubic specimens were designed for static splitting tensile failure tests at room and low temperatures (temperature range of 20~-90 ℃). The experimental results show that all the splitting tensile strengths of different type of concrete increase linearly with the decreasing temperature (with a maximum increase of nearly 130%), showing a significant low-temperature strengthening effect. The incorporation of basalt fibers can slightly improve the low-temperature strengthening effect of splitting tensile strength. All the splitting tensile strengths of BFRC with different fiber volume fractions show a certain fiber reinforcement effect, which can be enhanced with the increase of volume fraction. At extreme low temperature, the dominant failure mode of basalt fiber changes from pull-out failure to rupture failure, which can cause the enhancement of fiber reinforcement effect with the decreasing temperature. The size effect on splitting tensile strength increases with the decreasing temperature, while the addition of basalt fibers can effectively weaken the size effect (with maximum weakening degree of 25.8%). This study provides an effective reference for the applications of BFRC in engineering structures exposed to extreme low-temperature environments.