Using a novel method that couples genetic algorithm (GA) with numerical simulation, the geometric configuration for a two-dimensional slotted fin has been optimized in this paper. The objective of optimization is to maximize the heat transfer capacity of slotted fin, and minimize the pressure drop penalty of fluid flow through the fin. The key of this method is the fitness function of GA, which were (j/j(0))/(f/f(0)) and j/j(0). In this complex multiparameter problem, the numerical simulation is a crucial step to calculate the Colburn factor j and friction factor f. The results showed that for two-dimensional slotted fin considered, the j factor is increased by 229.22%, the f factor is increased by 196.30%, and the j/f ratio was increased by 11.11% at Re = 500 based on optimal integrated performance (j/j(0))/(f/f(0)); the j factor is increased by 479.08% at Re = 500 based on optimal heat exchange capacity j/j(0). The feasibility of optimal designs was verified by the field synergy principle. (C) 2011 Elsevier Ltd. All rights reserved.