Laser-assisted　TIG　arc　ignition　was　applied　by　1000　W　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.