Abstract: An analysis of separation costs supported the arguments of the claim that the separation sequence and heat-exchanger network could be determined separately. Based on this understanding of the problem, a new synthesis method was presented in this paper. First the optimal and near-optimal unintegrated sequences was found by means of the branch and bound strategy, and then the heat exchanger network was established by using 0-1 programming for each sequence. The sequence with minimal total separation cost defined the optimal energy-integrated distillation flowsheet. Computation efforts were considerably reduced, and the whole synthesis procedure could be accomplished on a microcomputer.