The tensile and shear properties of basalt fiber reinforced polymer（BFRP） and glass fiber reinforced polymer（GFRP） tendons after thermal aging were tested by the universal testing machine，and the effects of elevated temperatures on the mechanical properties and failure mode of BFRP and GFRP tendons were studied. Furthermore，the tensile strengths of BFRP and GFRP tendons after treatment under various elevated temperatures were statistically analyzed by Weibull model，and the thermal degradation mechanism of BFRP and GFRP tendon was quantitatively analyzed by a thermo-gravimetric analyzer. The results show that the color and morphologies of BFRP and GFRP tendons change obviously with the elevated temperatures. The tensile strength，ultimate strain，toughness and shear strength of BFRP and GFRP tendons slightly increase firstly and then decrease with the temperature，while the elastic modulus does not change significantly. Compared with the GFRP tendon，the BFRP tendon treated under the same temperatures exhibits lower tensile properties but better shear performances. The pyrolysis characteristics of BFRP and GFRP tendons properly explain the degradation mechanism of their mechanical properties after elevated temperatures.