Abstract: According to the frequency spectrum of magnetism- control transducing signal,it is found out that the frequency band of signal characterized the position of the seam is different from the interference signal.With regard to the realtime requirement of seam tracking system,a real-time wavelet denoising method was put forward based on sliding the fixed data window.In this way,a real-time data of arc transducing signal is taken dynamically.Through using decomposition method of orthogonal compactly supported wavelet and the 1^st and 2^nd layer's detail signal of the discarded arc tranducing signal,the amount of calculation is reduced,therefore the real-time of this method is guaranteed.Then DSP is used in the experiment on the actual welding current signal to check the denoising effect.It is shown that this method used in de-noising satisfies the requirements of de-noising and real-time.