Abstract: A pulsed CO₂ laser whose pulsed width is 10 ms was used to ignite the TIG arc,and a high-speed visual sensing system was established to detect the process of laser induced plasma triggering arc discharge and the shape of plasma.The experimental results show that,when the laser plasma contacts the cathode(tungsten rod) under action of electric field,which results in producing thermionic emission and field emission,the TIG arc forms self-maintaining discharge and is ignited.Furthermore,in order to investigate the influence of electric-field intensity in TIG arc on the performance of laser plasma triggering arc,the influence of main factors,such as tungsten electrode-tip shape,the height and the distance between electrode and laser etc.,on the performance for laser plasma triggering arc discharge were analyzed.