There are limited Vapor-Liquid Equilibrium（VLE） data in cluding N-formylmorpholine（NFM） for the design of the extractive distil lation process using NFM as solvent.The new interaction parameters of UNIFAC mo del were fitted with experimental data between CH2,ACH and NFM which was rega rded as a main group.Comparison of the prediction results of VLE data and infin ite dilution activity coefficients with other published methods of group divisio n for NFM, indicated more satisfying results with the interaction parameters of this paper. The four methods of group division for NFM were discussed based on the group division for ring molecule and group charge distribution. The group c harge distribution at the minimum energy state was calculated by the AM1 method in Chem3D Pro. The good theoretical basis was presented for the group division of NFM.
