Abstract: The tar−rich coal sample collected from the Badaowan Formation in the Baishihu Mining Area of the Santanghu Basin, Xinjiang was used in this study to investigate the component evolution and pyrolysis characteristics during the in situ pyrolysis. The methods employed included in situ pyrolysis physical simulation experiments, which were carried out under elevated temperature and pressure to measure the product contents at different temperature points. Overburden pressure pore permeability experiments were also performed to determine the evolution law of coal sample porosity. Furthermore, microscopic observations were made to examine the changes in maceral composition before and after pyrolysis, and COMSOL Multiphysics 6.2 software was utilized for multi−physics field−coupled simulation of in situ pyrolysis. Results show that semicoke yield continuously decreases as the temperature rises, while the tar yield exhibits a parabolic trend, initially increasing and then decreasing, reaching its peak at 400 ℃. The gas yield plus losses initially increase overall and then sharply decrease with the rising temperature. The overburden pressure pore permeability experiments indicate that a nonlinear fluctuating relationship exists between pyrolysis temperature, porosity, and permeability under pressure conditions. Significant differences are found in the semicoke maceral content after pyrolysis between bulk raw coal and small−particle pulverized coal. Both numerical and physical simulations jointly reveal that the evolutionary characteristics of the pressure field, porosity, and permeability over time and temperature are elucidated, with 400~600 ℃ being identified as the optimal temperature range for pyrolysis. This work can provide theoretical support for the underground in situ development of tar−rich coal resource.