Abstract: In order to improve the situation of discontinuity in the range of stresses caused by pin deformation, the mathematical theoretical model of peak contact stresses after pin node deformation in the test rig was established based on the Hertzian contact theory, and the pin node model was simulated and analysed using ANSYS software and compared with the theoretical model. The results show that the simulation results are in good agreement with the theoretical data. Combined with the actual engineering field application, five main indicators for reducing the peak stress in the contact area of the pin node hole wall were determined, namely: shaft hole gap, shaft casing thickness, node plate thickness, chamfer length, chamfer angle, and the use of Minitab software to establish the main effect cloud diagram for the three evaluation indicators: stress, tangential stress and strain; establish the affiliation function of the three evaluation indicators according to the fuzzy mathematical theory, and use the hierarchical Analysis of Hierarchy (AHP) was used to determine the weight vector of the evaluation indexes, and the optimal combination of parameters for the five main indexes was obtained by combining fuzzy comprehensive evaluation and the principle of maximum subordination, and the combination of parameters was simulated. The results show that the optimized pin node column peak stress reduction ratio is 58.77%, and the peak stress reduction ratio of the trunnion node is 12%. The optimal combination of solution parameters was applied in the field in the design and development of the 50 MN hydraulic support test stand, which verified the reasonableness of the optimised parameters and effectively improved the service life of the centre beam pin during the loading test of the hydraulic support test stand. It was further demonstrated that by adding slope chamfers to the pin nodes, setting reasonable initial clearances and plate thicknesses, the peak pin node loads could be reduced to a large extent and the length of the stress range improved, providing a reference for the practical engineering application of the design of plug-in and plug-out positioning pin assemblies for heavy equipment.