The issue of traffic congestion on single complex networks has been extensively studied in the past decade. Recently, interconnected network models have been developed to model the interactions between real-world systems. In interconnected networks, the coupling preference, i.e., the way to add coupling links, has great impact on the overall traffic performance. In this paper, we employ a simulated annealing algorithm to find a near-optimal configuration of the coupling links, which effectively balances the traffic loads and improves the overall traffic capacity.