In this study, we propose a method for estimating liquid–liquid equilibrium with ab initio molecular dynamics (MD) simulation. Additionally, we determined the non‐random two‐liquid model parameters for the systems applicable to the extraction design using a commercial software. The minimized energy of separate liquid phases yielded equilibrium data from a more versatile procedure than the existing MD simulation. Although many experimental measurements with the parameters have been published, the parameters are not always compatible with the software. The performances are graphically illustrated for example systems including ionic liquid and deep eutectic solvent, and the results indicated that the proposed procedures of the estimation and the model parameter determination were satisfactory.