Abstract: To solve the problems of low penetration capability, slow welding speed, and low welding productivity of traditional gas tungsten arc welding (GTAW), the ultrahigh frequency adjustable multi-pulse GTAW (UFMP-GTAW) process was proposed. The welding frequency of this process could reach up to 100 kHz, and the current change rate reached 150 A/μs. By introducing an intermediate current stage into the pulse welding current waveform, multiple current pulses were generated within a single welding cycle, and the time and amplitude of each stage of the pulse waveform were adjustable. An experimental platform for UFMP-GTAW was established to capture ultrahigh frequency welding arcs at different frequencies, which were then compared with ultrahigh frequency ordinary pulse welding arcs. Under the same average current, the high-frequency effect generated by the ultrahigh frequency current gave the arc a compression characteristic, making the temperature distribution of the welding arc more concentrated. Among them, the welding arc of 100 kHz UFMP-GTAW had the most concentrated temperature distribution. Finally, welding tests were conducted on Q235 steel. The results show that the 100 kHz UFMP-GTAW process can compress the welding arc and achieve a larger weld penetration depth.