In this paper, a methodology based on the finite element method is used to analyze the corona onset voltage on different structures of HVDC lines, the methodology includes atmospheric conditions such as pressure and temperature. The results obtained in simulations were verified through two experimental set-ups (rod-to-plane and corona cage) at sea level and 2200 m above the sea level. According to the results, the predicted values are in good agreement with the measured values in most of the tested configurations. Once the accuracy of the methodology was verified, it was used to modify the conductor bundle geometry of an HVDC line to maximize the corona onset voltage. The importance of this work is due to the prediction of the corona onset voltage since corona discharge in elements of a high voltage transmission line is an undesirable phenomenon because it causes power losses and electromagnetic interference.