Abstract: A finite element model of a piecewise contact flatness stress measurement process in cold rolling is established. Euclidean distance method is introduced to characterize the measurement error. The influences of relevant factors on measurement accuracy are analyzed in different flatness defect patterns, such as the bending of a flatness measuring roll, piecewise roll width, diameter of the roll, strip wrap angle, strip thickness, coiling tension, lateral distribution of coiling tension, and so on. Simulation results show that as the bending deformation of the strip flatness measuring roll increase, the flatness measurement accuracy is significantly reduced. A significant reduction of flatness measurement accuracy appear while the piecewise roll width increase; when the piecewise roll width decrease, the accuracy is improved more and more slowly. The greater the coiling tension, the higher the measurement accuracy. But when the coiling tension reaches a certain value, the accuracy no longer increase. As the asymmetry degree of coiling tension lateral distribution increase, the flatness measurement accuracy is reduced. The changes of the roll diameter, strip wrap angle, and the strip thickness do not affect the measurement accuracy.