A finite element method for calculating the radial force of oil seal considering the initial stress of spring was proposed,that is,the calculation of the radial force of oil seal with spring was realized by two-dimensional axisymmetric model.In this model,the oil seal spring was replaced by a circular tube,and the simulation of the initial stress of spring could be realized.The material properties of the tube model were obtained by the spring tension transformation in two states(the spring was assembled on the oil seal and the oil seal was assembled on the shaft),and the finite element calculation of the radial force of the oil seal with spring was realized.The correctness of the calculation results was verified by the radial force measuring instrument test.Through analysis,it is found that the radial force generated by springs is not converted into oil seal radial force by one hundred percent.