A simulated annealing-based approach to synthesis of multi-component distillation systems is developed. An encoding procedure that makes use Of all integer number series is developed to represent and manipulate the flow sheet Structure of the system. With the representation procedure, the overall synthesis problem is formulated as all implicit mixed-integer nonlinear programming (MINLP) problem. A simulated annealing approach suitable for MINLP optimization is adopted and improved to solve the problem. Four example problems, including large-scale ones are solved to illustrate the approach. (C) 2008 Elsevier Ltd. All rights reserved.