With increasing power and efficiency of rotating machinery, seal whirl instability is attracted more and more attentions.A large number of studies are based on lumped parameter model.In this paper, a continuous rotor model acted by oil film force and seal force is established by using the Euler-Bernoulli beam theory.To analyze the dynamics of the continuous system, the governing partial differential equation (PDE) is usually converted to a group of ordinary differential equations (ODE) by the traditional Galerkin method (TGM).