Abstract: Finite element model of pitting during spot welding process was established to study the effect of pitting on temperature and stress distribution on electrode face,and corresponding experiments were carried out.The results show that higher temperature and pressure are produced at pitting area,which reduce electrode life.Micro-crack is also easily produced in pitting area at the higher temperature and pressure;through the crack,metal elements in galvanized coat are filtered into electrode,which accelerate electrode invalidation.