Abstract: This article took a tensiometer looper during hot rolling as the object of study. A three-dimensional finite element model was built for a tensiometer looper with roller-height-difference and a hot rolling strip. Considering roller-height-difference as a basic variable, the measurement error of flatness caused by roller-height-difference and its distribution rule under different situations were obtained by changing the arrangement of high and low rollers, the strip thickness, and the average tensile stress of the strip.