Abstract: Addressing the different cold-crack trends of the 13Cr stainless steel pipes with different Mn contents, the effect by Mn content on the cold-crack sensibility of the 13Cr stainless steel tubing is studied and the causes for after-rolling cracking of it are explored by means of separately measuring the influence of Mn content on phase transformation temperatures and volume effects of the longitudinal, radial and circumferential specimens of the pipe, and the stress analysis of the phase transformation process thereof. The results show that the martensitic transformation temperature (Ms) falls down, while the volume effect grows up as the Mn content increases, among which, the radial specimen presents the most significant change in length which leads to the increase of the circumferential tensile strain of the as-rolled pipe during the martensitic transformation process, ultimately causing excessive circumferential tensile stress on the outer surface of the pipe, and thus resulting in increase of the cracking risk.