Abstract: Laser-assisted TIG arc ignition was applied by 1000W semiconductor laser.Using emission spectroscopy method,the arc ignition process of the spectral information at different moments was observed,while the transient characteristics of electron density were obtained by Stark broadening method.The results show that,in the arc ignition process,the contribution of electron from different elements is obviously different.In the beginning of arc ignition,the contribution of electron was from the ionizing metallic element,as time increasing,the contribution of electron from gas was gradually increased,and for the existence of the electric field between electrodes,high-temperature gas quickly formed a cascade of ionizing and finally arc was established.