Abstract: Microwave-assisted mechanical rock breaking is an important means to achieve non-blasting continuous mining of hard rock. The microwave irradiation is of important theoretical and practical significances for studying the temperature response and failure mechanism of rock. For the granite samples subjected to microwave heating, the unilateral and double-sided heating tests with different power and time as well as the P-wave velocity tests before and after heating of the samples are carried out. The results show that the reverse power of the samples decreases with time as a whole, and the degree of decrease increases with the increase of power. The internal temperature of the samples is higher than the surface temperature, and the change has obvious phase characteristics, and there is an "inflection point" in the temperature rising phase, and the surface temperature gradually decreases from the center to the edge in the radial direction. Microwave heating causes thermal stress inside the samples and generation and propagation of cracks, reducing the P-wave velocity. Heating the samples with a single, single-sided, high-power and short-time microwave irradiation method can increase the temperature of the samples more significantly.