Abstract: Shortcomings of using singleobjective optimization to solve the job shop multirow facility layout problem are analyzed. With this in mind, multiobjective optimization for job shop multirow facility layout problem is discussed. A multiobjective combinatorial optimization model with both material handling cost and space utilization considered is developed. Then, a modified genetic algorithm (GA) is proposed to solve it. The encoding, reproduction, and fitness functions are well designed for all three situations: automatic newrow layout, tworow layout, and threerow layout. A case problem from the industry is presented to show the application of the proposed method. With coding by Matlab, performance is compared with that obtained by singleobjective methods. It shows that it outperforms the singleobjective methods in applicability and computational efficiency.