Abstract: The choice of electrode material directly influences the quality of resistance welding. The commonly used Cr-Zr-Cu alloy is widely employed in electrode manufacturing due to its excellent electrical conductivity and mechanical properties. However, in continuous spot welding operations, the wear of the electrode tip leads to an increase in its diameter, which directly affects the nugget diameter and subsequently the quality of the weld. To investigate this phenomenon in detail, this study employs ABAQUS software to construct a simulation model for resistance spot welding of 1.5mm thick 1Cr18Ni9Ti material. The study examines how variations in electrode diameter (6mm, 7mm, and 8mm) impact the temperature distribution during welding by simulating the changes in the temperature field. The simulation results indicate that under fixed welding pressure and welding time conditions, as the electrode diameter increases, the temperature in the weld zone decreases, resulting in a gradual reduction in nugget diameter. Notably, when the electrode diameter reaches 8mm, the temperature in the weld zone does not reach the melting point of the metal, causing the nugget to disappear and the electrode to fail.