▎ 摘　　要

We investigate theoretically surface plasmon polaritons (SPPs) dispersion relation for the configuration of an anisotropic dielectric medium sandwiched by two symmetric graphene layers and isotropic dielectrics. The dispersion splits into odd and even modes in the system. We show that the proper oriented optical axis of the dielectrics can enhance the confinement, propagation length and figure of merit (FOM) of two modes. And the proper orientation for propagation length of two modes and FOM for odd mode depends on the normalized separation of the graphene layers. The effect of the anisotropic dielectric between the two graphene layers is much greater than that outside the two graphene layers.