Carried out in microcanonical (NVE) ensemble, the Z method locates the melting boundary through overheating until melt, and the observed minimum temperature that the system relaxes to the liquid is taken as the melting point of the material. In these approaches, the melting curves depend strongly on the selected empirical potential parameters. Different potential parameters can produce different melting curves. Most potential parameters were only fitted to the properties of solid phase. However, if they were fitted to those of both solid and liquid phases, one could correctly reproduce the melting curves of materials. In this work, we propose to compare these three techniques to estimate the highpressure melting line of iron in MD simulations. We hope this study can contribute to understand the melting behavior of iron under Earth’s core conditions.