Abstract: Welding electrical signals are used directly by arc sensor to track weld seams. Rotational arc has great importance because it can be further used to improve the weld bead appearance. The current signals are simulated based on the mathematical model of gas metal arc welding (GMAW) and the dynamic model of wire tip motion. Welding experiments with different welding parameters have been performed and the welding waveforms have been acquired. The results show that the simulated current waveforms are consistent with the acquired waveforms in experiments. The asymmetry of current waveform in each arc rotating cycle is proportion to the torch deviation. The higher the arc rotating speed is,the smaller the current amplification is. The bigger the rotating radius is,the higher the sensitivity of the arc sensor is. The results of this work are helpful to the design and application of high speed rotational arc sensor systems.