Abstract: In order to study the heat dissipation of electrode during the spot welding process, the heat input mechanics of electrode for spot welding was analyzed in detail firstly.Then, the heat input model for electrode was built based on the finite element method (FEM)and the information of heat input during the welding process was analyzed.Finally, experiment was carried out to validate the conclusion.It's found that the dissipating heat of electrode was made of resistance heat and conduction heat.The resistance heat had the same law with the welding current and the conduction heat was the major part of the dissipating heat.This research is helpful to the further study on heat dissipation of electrode and quality control of spot welding.