This paper presents some aspects of overvoltage waves propagation on high voltage transmission lines structures. The paper presents EMTP simulation of selected 110 kV and 330 kV transmission lines for fast front lightning overvoltage waves. Computer simulation results shows, that the geometrical parameters of line tower separate modules (upper level – middle level – lower level) may detailed simulation process of lightning surge and effected modeling results. Quantitatively, for operating in Latvia power lines, the difference between tower different parts can be up to 50 kV (for 110 kV power lines) and up to 60 kV (for 330 kV power lines), taking to account critical value of lightning current (35 kA), that has a significant impact of the calculation processes of the degree of power lines protection from lightning surges. The highest voltage values were acertained on 110 kV and 330 kV line towers upper levels - 370 kV and 390 kV respectively, but lowest on lower levels 320 kV and 330 kV respectively. A diference between those two cases is phases levels location on different height and tower footing impendance diference. The surge impedance of the tower is 170 Ω for 110 kV tower and 230 Ω for 330 kV tower. The particularized simulation of transmission lines towers elements enables monitoring a reaction of electrical network to the propagation of the lightning overvoltage travelling waves. The process of the simulation development consists of the formation of an initial electrical network; it comprises also the determination of all elements of the transmission power network.