The perturbation expansion method is employed to study the heat transfer ofnonlinear composite media. Potentials on phase surfaces of composites are not continuous because of thermal contact resistance. The study shows that the perturbation expansion method is also applicable to the case of nonlinear system with potential discontinuity between different phases. As an example, we apply the method to calculate the temperature field of nonlinear composite media with an cylindrical inclusion embedded in a matrix and discuss several typical cases of temperature distribution in detail.