According to the ACI 440.3R—04, accelerated aging tests for evaluations of tensile properties of glass fiber reinforced plastic(GFRP) rebars exposed to alkaline solution were conducted. 150 GFRP rebars were used in the test and the test parameters included: （1） temperature of alkaline solution at 40, 60 and 80℃;（2） diameters of GFRP rebar were 12.7, 16.0， 19.0 mm; （3） immersion period was 3.65, 18, 36.5, 92， 183 d, respectively. The results show that after being exposed to alkaline environment for 183 d at 40, 60 and 80℃, tensile strength of GFRP rebars with diameter of 16.0 mm decreased by 34.97%, 4881% and 68.85%, respectively. After being exposed to alkaline environment for 183 d at 60℃, the attenuation value of tensile strength of GFRP rebars with diameters of 12.7, 16.0， 19.0 mm were 56.08%, 48.81% and 47.08%, respectively. With the increase of immersion period, the tensile strength and elongation of GFRP rebars exposed to alkaline environment at 40, 60, 80℃ decreased, and the higher the temperature, the greater the decay rate. The microstructure of the GFRP rebar surface was surveyed under scanning electron microscopy(SEM), and it indicated that the interface between fiber and resin of GFRP rebars in the corrosion region become loose and a clear debonding phenomenon appears, with the temperature increased, the interfacial debonding of GFRP rebars become more obvious. Finally, based on the Arrhenius equation, tensile strength prediction model of GFRP rebars under alkaline environment was proposed.