Abstract: Based on many experiments of CO2 laser welding of zinc coated high strength steel to vehicle body,joint microstructure and stress-strain curve of specimen were acquired.In the course of experiments,the sort of welding protective gas was selected,the influence of technological parameter on material melting characteristic of deep penetration welding was analyzed.By adopting blowing side protective gas,the problem that gas hole was easy to form owed to evaporation of zinc and moisture of circumstances in laser welding was solved.The experimental result indicated that deep penetration laser welding could effectively avoid softening heat affecting zone,control the gas hole and restrain joint flaw of welding of zinc coated high strength steel by blowing side protective gas.