The thesis is aimed on the computation of the electrical parameters of the overhead transmission lines on high voltage levels. It is based on the theoretical background introduced by J. Carson in 1926. It also has a different angle of view in means of the critical discussion on the zero sequence calculations, depth of the ground current, uncertain initial computation conditions or evaluation of the calculus approximation. The final chapter is also discussing the connection between electromagnetic and circuit theory. All the mentioned topics are set to lead the dissertation thesis results into the actual application in practice.