This thesis studies a mixed integer programming for solving the facility location problem. A model is proposed for the optimal location of facilities in the multi-stage distribution system under the given demand requirement constraints at minimum total cost. First, the problem is reformulated in such a way that a heuristic integer solution for the associated continuous problem can be obtained through by simple and unified dual-based procedures. Second, the heuristic procedure for improving integer solution is implemented. In addition, the efficient simplification procedures are considered. Basically, the branch and bound (B\&B) technique is used to optimize the model. This study may be successfully applied to solve the practical multi-level location problems, where capacities of facilities are assumed to be unlimited.