The phenomenon of buckling is attributed to the non-uniform stress imposed on strip. This paper investigates the occurrence of this non-uniform by calculating the stress distribution in circumferential and axial direction. The results indicate that stress distribution is even in circumferential direction, and the non-uniform happens in the axial direction. Furthermore, this non-uniform is quiet related to the proportion of strip width and the roll flat part length. Meanwhile, the roll flat part length should as long as it could be in the context of insuring the enough centripetal force to prevent the snaking.