The primary problem in arc welding using rotating arc sensor is filtering and extraction of the signal during the welding process.The basic principle of arc sensor and welding signal characteristics are introduced.The general digital filters of the rotating arc signal and the comparison of the filters in experiments are produced.An effective combination of signal filtering method applied in rotating arc sensor is put forward.Experiments prove that this method can more effectively restrain the interference of the arc signal and retain the useful information of signal characteristics.