The effect of temperature on rock properties has attacked wide attention with the development of deep earth engineering. The change of temperature results in brittle-ductile transformation and makes the fracture toughness different. In the current study, a modified elastic–plastic damage model is proposed to predict the constitutive relation of granite in tension at different temperatures. The model is applied to predict the J-integral of a double-edge-notched plate. Unloading at the point where slope of the secant line is 0.95 times of the initial linear segment slope, the elastic and plastic part of the J-integral can be distinguished. It is noted that the J-integral decreases with elevated temperature and the downward trend changes obviously at around 600 °C. The plastic part takes 57–73 % of the total J-integral for quasi-brittle materials at different temperatures. The fracture toughness predicted based on different methods is compared, it shows that the fracture toughness predicted by the J-integral method is about 1.43 times of the ASTM load-based method.