1720 mm cold rolling skin pass mill has shape defects frequently, especially in the production of electrical steel, the amount of shape unqualified exceeds 5%. In order to improve the precision of shape controlling, considering the technology characteristics of this unit and taking the uniformity of forward pull of exit of the belt materials and the transverse distribution of draught pressure as the objective function, new contours of work roll and backup roll are designed. Productive practice shows that the contact width between work roll and backup roll is changed with the change of strip width, the contact pressure becomes more homogeneous, the control by bending roll and the strip shape are improved, which creates great economic returns for the field.