The problem of propagation of electromagnetic waves in a inhomogeneous dielectric layer coated on one side with a layer of graphene, which is considered to be infinitely thin, is considered. The main problem in describing the process of wave propagation in a waveguide structure is to obtain a properties of the propagation constants. Maxwell’s equations are solved in the frequency domain. The conjugation conditions contain the conductivity of graphene. In this work, we neglect the nonlinearity of graphene. The results of calculations of propagation constants depending on the parameters of the problem are presented.