Abstract: In the TIG-MIG hybrid welding, the first ignited TIG arc can assist MIG welding to achieve the non-contact arc ignition. And no welding spatter was produced during the whole process of non-contact arc ignition. The arc voltage, welding current and arc images during the process of the MIG arc ignition were acquired by a synchronous acquisition system of electrical signals and high-speed video, then the effect of the first ignited TIG arc and the parameters variation on the MIG arc ignition process and ignition modes was studied. The results showed that the critical point to realize the non-contact ignition of MIG arc with the assistance of the TIG arc was the filamentary discharge channel formed between the MIG wire tip and the TIG arc. The non-contact ignition of MIG arc with the assistance of the TIG arc presented good adaptability to the variation of TIG welding parameters. In addition, based on the streamer theory of gas gap breakdown, the formation of filamentary discharge channel was discussed, and thereby the mechanism of realizing the non-contact ignition of MIG arc with the assistance of the TIG arc was revealed.