To achieve the goal of industry 4.0 for steel industry, intelligent automated manufacturing becomes increasingly important. One of the key steps on the automatic production line of steel products is automatic inspection of surface detects. In this paper, we consider the problem of stitching continuous casting steel billet images captured from billet production line. It has been shown that integrated individually captured continuous billet images would be beneficial to vision-based surface inspection. This paper presents a fast image stitching fr amework for continuous billet images relying on homography estimation. Experimental results have demonstrated that our method achieves fast image stitching with accurately stitched results.