The pin joint connection is the main connection form of the hydraulic support structure,and its reliability has an important effect on the normal use of the hydraulic support.Based on the Hertz contact theory,a theoretical model of the contact stress at the pin hole was established; ADAMS was used to analyze the force of each structural member of the hydraulic support to obtain the force of the pin hole; the contact stress,deformation and plastic strain at the pin hole were analyzed based on the finite element method.The results show that under the torsion of the top beam and the base,the contact stress of the pin joint connection exceeds the yield limit of the material,and the contact stress distribution has a strong nonlinearity; the pin hole stress is mainly concentrated in the front contact part of the pin hole,the plastic strain of the hole is concentrated on the contact part of the pin hole,which shows the squeezing effect;under the positive tension,the plastic strain on both sides of the pin hole is more obvious.