Given the challenges faced by in-situ pyrolysis of tar-rich coal,such as high ground stress,complex geological conditions,anddifficult analysis of pyrolysis products,a high-temperature triaxial test device was designed and built independently to simulate the in-situpyrolysis process of tar-rich coal. The test device includes a high-temperature and high-pressure gas supply module,an in-situ pyrolysismodule,a servo control module,and a product separation and cooling module. Taking the Shenfu tar-rich coal in Northern Shaanxi Province as the research object,the pyrolysis experiments of high temperature and high stress under different burial depths were simulatedbased on the high-temperature triaxial test device. The results show that the high-temperature triaxial apparatus can provide axialcompression of 0~15 MPa (buried depth of 0~600 m). The loading response is rapid,and the stress can remain stable duringpyrolysis. During the experiment,the high-temperature triaxial apparatus can heat the central temperature of coal samples over 600 ℃,and can realize the pyrolysis experiment of tar-rich coal at the set temperature. When the simulated burial depth increased from 100 m to300 m,the axial stress on coal samples increased from 2.45 MPa to 7.35 MPa,the yield of pyrolysis semi-coke risen from 67.70% to68.04%,and the tar yield first increased and then decreased,with the highest value of 6.50%. With the increase of simulated burial depth,the contents of light oil and phenol oil in tar gradually increased from 19% and 9.5% to 25% and 12% respectively. The proportion of pitchin tar is reduced from 25% to 20%; The aromatic hydrocarbon content increased from 32% to 38%,and the aliphatic hydrocarbon contentdecreased from 28.5% to 19.3%. The permeability of coal seam decreases with the increase of stress,which hinders the heat and masstransfer in the pyrolysis process,leading to the increase of residence time of pyrolysis products of tar-rich coal,the secondary reaction oftar,the fracture of long-chain aliphatic hydrocarbon compounds and the transformation of methyl and methylene into small molecularcompounds. On the other hand,stress promotes the condensation reaction of tar molecules and the content of polycyclic aromatichydrocarbons increases rapidly. The increase of in-situ stress improves the yield of light aromatics and coke,and the quality of tar isimproved to light weight.