Skeleton oil seal is a part of steel and rubber materials in combination,and the parametric model of rubber product is difficult to control due to the existence of the shrinkage rate in all places during vulcanization process.The regularity of contracted variant of rotary skeleton oil seal product was analyzed,and the lip area of oil seal was researched mainly,where the variant was the most complicated in the process of mold design.By solving the mathematical relationship of each parameter at the lip area,the mathematical relationship model of those parameters which related to the contracted variant of the area was established.The full size were constraint on three dimensional(3D)model of the oil seal as well as the corresponding model’s cavity,so as to get the correct shape of the mold cavity on the basis of ensuring contracted variant model of products.The result of the research provides a feasible approach on the intelligent design about rotary skeleton oil seal.