In order for optical interconnection technologies to be incorporated into the next-generation parallel computers, new optoelectronic computer-aided design, integration, and packaging technologies must be investigated. One of the key issues in designing is the system volume, which is determined by maximum interconnection distance (MID) between PEs. A novel 2-D genetic algorithm was presented in this paper at the first time, and used to solve the placement of twin-butterfly multistage networks based on transmissive physical model. The experiment result shows that this algorithm case works better than other algorithm cases.