Abstract: Based on the characteristics of the manufacturing process for the seamless steel tube,the major reasons for the quench-caused crack of the tube is identified via analysis of both the macro-morphology and the microstructure of the tube, i.e., the surface defect, the stress-induced cracking, and surface carbon pick-up. And the development mechanism for different quench-caused cracks are analyzed, and accordingly the preventive action are proposed. The analysis also leads to such a conclusion that the occurrence rate of the quench-caused crack of the seamless steel tube is expected to be remarkably reduced by means of improving the as-rolled tube surface quality,optimizing the quenching process parameters,and enhancing the homogeneity of the billet,etc.