Abstract: Temperature is the main factor influencing the changes of reservoir rocks and fluid properties during fire flooding. In order to subdivide the changes in each phase of fire flooding, the paper uses the thermogravimetric-differential scanning calorimetry method to characterize oxidation process of crude oil, and studies rock evolution and its influences on reservoir properties at different temperature intervals by using X-Ray diffraction and back scattered electron imaging technologies. The study results show that there are 4 critical temperatures during fire flooding, i.e., crude oil oxidation activation, high-temperature combustion threshold, thermal activation of rock, and deep rock metamorphism, and the rock evolution can be divided into 5 phases such as formation preheating, low-temperature oxidation of crude oil, medium-temperature crude oil oxidation and clay decomposition, high-temperature crude oil oxidation and clay sintering, and deep metamorphism of non-clay minerals, among which the phases of high-temperature crude oil oxidation and clay sintering are the maximum mobility period during the evolution with the released heat of crude oil combustion accounting for about 60% of the total released heat, and the clay minerals have sintering, resulting in the obvious changes of reservoir pore structures and properties