Abstract: On-line process monitoring is beneficial for maintaining high quality products at high production rate and low cost. The traditional off-line weld testing is costly in terms of time, material, and productivity. Real-time nondestructive testing, however, can be as accurate as off-line testing; yet faster, cheaper, and better productivity. In the field of real-time monitoring, various methods have shown their prospects in detecting gas shielded tungstens arc states. In this paper, a new technical way for real-time weld process monitoring based on image analysis with DSP is presented. The focus is on how to decrease the effect of the arc light and make the system more faster (≤50ms) and more accurate (≤10μm).