Abstract: In-situ pyrolysis of tar-rich coal is an innovative coal utilization method that heats coal seams by isolating air to extract oil and gas resources. This approach plays a crucial role in improving domestic oil and gas supply and ensuring national energy security. To investigate the temperature distribution pattern during the in-situ pyrolysis of tar-rich coal, a self-designed pyrolysis experimental apparatus was used to simulate the temperature field evolution in the underground pyrolysis process of tar-rich coal. Scanning Electron Microscopy (SEM) and 3D Microscopy (3DM) were employed to analyze the temperature response and thermal relaxation characteristics of the tar-rich coal seam and its overburden, revealing the heat transfer mechanisms within the strata during the pyrolysis process. The results show: During the pyrolysis of tar-rich coal, the temperature at different locations increases non-linearly with time. The temperature variation in the coal seam and overburden follows a similar pattern, with diffusion in the vertical direction occurring faster than in the horizontal direction. Both the coal seam and overburden exhibit significant thermal relaxation. The temperature in the central area is higher and increases rapidly, while the temperature at the periphery is lower with a slower rate of increase. The extent of thermal relaxation is related to the anisotropy of the coal-rock body and spatial position. The further the distance from the central axis of the pyrolysis zone, the longer the secondary heating time of the strata.During the pyrolysis process, the development of pores and fractures in the pyrolyzed semi-coke, along with an increase in fracture network density, reduces the thermal conductivity of the tar-rich coal, forming sealed spaces and causing the retention of pyrolysis tar within the coal matrix. At the same time, due to the high density and viscosity of the pyrolysis tar, it condenses in the lower sections of the coal seam and low-temperature areas, causing partial cementation of the semi-coke into lumps and forming insulating layers. This reduces heat transfer efficiency, impacts the depth and rate of the pyrolysis reaction, and leads to a conical temperature distribution pattern in the coal and overburden. The research findings provide significant theoretical support for the engineering practice of in-situ pyrolysis of tar-rich coal.