Basalt fiber reinforced high-strength mortar (BFHSM) has a bright prospect of applications in engineering due to its lightweight, high strength, and great durability. The mechanical properties and durability after high temperature are important indicators for evaluating structural safety performance. In this paper, the effect of temperature (20, 100, 150, 200, 250, 300, 350, 400 ℃) on the mechanical properties and the chloride ion penetration resistance of BFHSM with basalt fiber (BF) content of 0% (volume fraction, the same below) and 1.0% were investigated by high temperature test, compressive strength test, splitting tensile strength test, XRD analysis, and chloride ion penetration resistance test. The results show that the compressive strength and splitting tensile strength of BFHSM increase first and then decrease, and the compressive strength and splitting tensile strength can be improved with BF. XRD results indicate that the hydrated calcium silicate (C-S-H) gel, dicalcium silicate (C₂S) and tricalcium silicate (C₃S) in BFHSM matrix gradually decrease after the temperature exceeds the critical temperature, which is the main reason for the decrease in compressive strength of BFHSM. Also, the incorporation of BF can improve the chloride ion penetration resistance of BFHSM. Compared with the control group, the electric flux of BFHSM decreases by 19.82%, 5.33%, 7.61%, and 2.21% after 20, 100, 200 and 300 ℃, respectively. Moreover, the chloride ion penetration resistance of BFHSM decreases with the increase of temperature.