The total cathode voltage drop(CVD) takes a percentage of about 7-9 of the overall cell voltage for a modern Hall-Heroult cell running at 320kA or 350kA. It represents a significant fraction of the cell's overall power consumption. A nonlinear electric contact model based on finite element method was set up which was successfully used in the analysis of CVD in Hall-Heroult cells, including the analysis of the impacts of graphite content, cathodic structure and ledge growth/muck formation on CVD. Results show that CVD can be reduced about 70 mV if semi-graphitic blocks are replaced by graphitized blocks. A cathode block structure with two full-length collector bars shows not much cathode drop advantage compared to two split bars. CVD increases with longer ledge extended across the cathode and is affected slightly by muck coverage on the cathode