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To explore the effect of the joint contact area and temperature on the dynamic property of rock joints and wave propagation in granite rockmass, an impact test of a jointed granite specimen was conducted with a split–Hopkinson pressure bar. The jointed specimen was composed of an artificially grooved specimen and an intact specimen. The ratio of the joint contact area to the cross-sectional area of the intact specimen was defined as the joint matching coefficient (JMC). The specimens were heat-treated at temperatures of 25°C, 200°C, 400°C, and 600°C. The experimental results showed that with the decrease in the JMC, the nonlinear characteristic of the stress–strain curve for the initial loading segment was more evident for the heat-treated specimen at a constant temperature. Furthermore, the transmitted coefficient, secant modulus, and joint-specific stiffness gradually decreased. For a given JMC, the expansion of the mineral component in the specimen heat-treated at 200°C caused the internal cracks to close, resulting in a larger transmitted coefficient and joint-specific stiffness. For the specimens heat-treated at 400°C and 600°C, the transmitted coefficient and joint-specific stiffness gradually decreased owing to thermal damage. In addition, the deformation of the jointed specimen at different temperatures was mainly caused by joint closure. A smaller JMC or more serious thermal damage led to an increase in the peak value of the joint closure. [ABSTRACT FROM AUTHOR]