Microwave-assisted rock breaking can effectively reduce cutting tool wear and improve breaking efficiency, which has a broad prospect of engineering development. 10 kinds of igneous rocks were heated under microwave irradiation. The results illustrated that the heating rate depends on mineral species and content as well as the Fe content. The heating rate is higher when the rock contains more sensitive minerals and Fe. Generally, basic rock has the highest heating rate, followed by intermediate rock, acid rock the lowest. This phenomenon is related with the law of mineral and element composition in igneous rocks. Heating prediction model of rock was proposed based on experimental study. Except for mineral species and content, ratio and structure correction coefficients related to the temperature increment were also taken into consideration. In the heating prediction model, the ratio correction coefficient of sensitive mineral is bigger than 1, decreasing with the rise of its content, and eventually tending to 1. The ratio correction coefficient of non-sensitive mineral is smaller than 1, increasing with the rise of its content, and eventually tending to 1. The heating rate of block is twice to three times that of powder. The structure correction coefficient of basic rock is bigger than that of intermediate rock and acid rock.