Abstract: In order to analyze the influence of boron nitride (h-BN) doping on the thermo-mechanical properties of epoxy resin (EP) from the microscopic point of view, diglycidyl ether of bisphenol A (DGEBA) and 4, 4'—diaminodiphenyl sulfone (4, 4'—DDS) were used as epoxy matrix and curing agent, respectively. The changes of thermo-mechanical properties and microstructure parameters of h-BN modified epoxy resin before and after modification were studied and analyzed in the temperature range of 250~450 K by a molecular dynamics method. It is found that the addition of h-BN to epoxy resin can improve the thermal conductivity, glass transition temperature, Young's modulus and shear modulus of epoxy resin material, reduce the thermal expansion coefficient, and achieve the purpose of improving the thermal conductivity, thermal properties and mechanical properties of epoxy resin. The thermal conductivity of epoxy resin and h-BN/EP composites will be improved by increasing temperature, but the thermal conductivity of pure epoxy resin will be more significantly affected by rising temperature. At the same time, the mechanical properties of epoxy resin and h-BN/EP composites are worse due to temperature rise, but the mechanical properties of h-BN/EP composites are always better than those of pure epoxy resin within the temperature rise range of dry on-board traction transformer. In terms of microstructure parameters, the MSD of the epoxy resin is significantly lower after the addition of h-BN, and the free volume distribution of the h-BN/EP model is less likely to disperse with the increase of temperature than that of the EP model, indicating that the addition of h-BN will hinder the movement of the molecular chain of the epoxy resin.