– With the rapid increase of design complexity and the decrease of device features in nano-scale technologies, interconnection optimization in digital systems becomes more and more important. In this paper we develop a simultaneous FU and register (SFR) binding algorithm for multiplexer optimization based on min-cost network flow. Unlike most of the prior approaches in which functional unit binding and register binding are performed sequentially, our approach performs these two highly correlated tasks gradually and concurrently. We also present an ILP formulation of the combined functional unit and register binding problem for the optimality study of heuristics. Experimental results show that when compared to traditional binding algorithms, our simultaneous resource binding algorithm is close to optimal solutions for small-size designs (only 5% more MUX) and achieves significant reduction for MUX area (12%) and timing (10%) for a set of real-life benchmark designs.