Abstract: ：Nonlinear transmission line equation is solved by the trial function method. By introducing transformation and selecting appropriate trial functions, the nonlinear partial differential equation that is hard to be solved by the usual ways can be reduced to a set of algebraic equation, which can be easily solved, and its related coefficients can be easily determined by the method of undetermined coefficient. Finally, the analytical solution of the equation is successfully derived.

Key words: trial function method, nonlinear transmission line equation, exact solution