Abstract: The welding process of three arc welding machines had been tested and analyzed with the welding dynamic arc wavelet analyzer developed by the anthers.The experimental results indicate that the instantaneous energy can synthetically reflect the influence of current and voltage on dynamic arc characteristics.To make are ignite successfully, the instantaneous energy should increase to enough high quickly along with the current.In a cycle of short circuting transition during the steady welding process, the instantaneous energy during arc burning should be kept at the constant base, and then it falls to smaller value rapidly, finally, it rises rapidly and completes the short circuit transition. The instantaneous energy falls again rapidly to base after arc re-striking.While arc extinguishing, the instantaneous energy falls slowly to zero and avoids serious impulsion.The experiment results can provide for the foundation to design and control accurately the waveform of the welding current and voltage.