Objective To analyze the influence of different materials on thermal stress field of the bipolar high-frequency electric knife. Methods The electric-thermal coupling simulation analysis was performed for thermal stress field in working process of the bipolar high-frequency electric knife. The influence patterns for 4 kinds of insulating layer materials 304 stainless steel, 316 stainless steel, 317 stainless steel, Ti6Al4V and 4 kinds of electrode materials polypropylene (PP), polyamide-6 (PA6), polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) on thermal stress field and thermal deformation field of insulating layer, electrode and coating of bipolar high-frequency electric knife and myocardial tissues were studied. Results The thermal deformation of myocardial tissues was much higher than that of the components of high-frequency electric knife in period of 2 s for continuous power. In terms of myocardial tissue protection, 304 stainless steel was the best electrode material for high-frequency electric knife. For choosing PP as the insulating layer material, thermal deformation of myocardial tissues caused by thermal stress was the smallest, which could better maintain the integrity of myocardial tissues. Conclusions The manufacturing materials of high-frequency electric knife have an important influence on thermal stress field in its working process. The regularity analysis results can provide guidance for the development of high-frequency electric knife.