Abstract: Based on the technology of edge detection by wavelet transform,a new method of detecting seam of welding pipe using Gauss wavelet is proposed.As Gauss wavelet has local characteristics on the time and frequency domain,it is suitably used to detect the local shape of a signal as welding seam.The paper mainly relates to the pretreatment of the seam image,the Gauss wavelet transform and its application on the detecting welding seam,and the correlation analysis on the ultimate results.The scale parameter has outstanding effects on the transform results.By the analysis and the simulation on computer,the method shows higher estimated precision and better capability of anti disturb.In the other hand,its complication is not high.So it can be used into real time control system.