As important strategic replacement resources in China，shale oil and gas are the main force for increasing oil and gas reserves and production in the future. However，given the development of micro/nano-scale pores in shale matrixes，reservoir stimulation is required for its flow capacity improvement，so as to achieve efficient development of shale reservoirs.Heat treatment technology，which is green and environmentally friendly，is a new approach to reservoir stimulation and recovery enhancement. It is capable of improving the physical properties of shale by generating heat energy in formations，thereby enhancing the seepage capacity of reservoirs. Therefore，it is of great significance for reservoir stimulation to accurately understand the shale reservoir stimulation mechanism and grasp the change laws of physical properties of shale in a thermal environment. With the help of the characteristics of shale oil and gas reservoirs，the shale reservoir stimulation mechanism under heat treatment was analyzed after the research results regarding pore structure changes in shale during heat treatment was investigated in China and abroad. The results show that the non-uniform thermal expansion of rocks and minerals produces thermal stress，which leads to thermal expansion of fractures. The pyrolysis of organic matter gives rise to the development of organic pores，and the pressurization due to the evaporation of pore fluids and the water-rock interaction both promote the increase in pore space of rocks. Through the above mechanism，the internal storage space of reservoirs is increased and the conductivity is enhanced，as a result of which the effective exploitation of shale oil and gas can be realized. Besides，this paper summarizes the change laws of physical and mechanical properties of shale under thermal stress. Specifically，the porosity and permeability of shale increase significantly at high temperatures. Under the condition，the average pore diameter inside the shale increases，and a large number of micro-fractures develop to form a complex fracture network. The overall strength of shale is reduced and the plasticity is enhanced，which facilitates hydraulic fracturing，heat treatment and other measures to increase production.