The strip slipping occurred frequently in the speed-up process of the skin pass mill in a factory, which seriously affected the surface quality of the strip. Based on the analysis of production process data, a method for judging the position and time of slipping between strip and bridle roll was proposed. Furthermore, a mathematical model of the movement between the strip and the bridle roll of the skin pass mill was established, and the main factors affecting the strip slipping in the speed-up process were analyzed. It was found that a small friction coefficient of bridle roll, a large speed and acceleration of the leveler and a large tension difference of the bridle roll assembly will increase the slipping risk between strip and bridle. The measures to solve the strip slipping problem were also put forward. The incidence rate of the strip slipping in the speed-up process was reduced from 3.33% to 0.17% after optimization, which played a positive role in the stable production of the skin pass mill.