The distribution center connects the flows of upstream (ie. Plants) and downstream (ie. retail stores) of the logistics system. A well-designed network flow can decrease the transportation cost as well as provide diversified needs for the customers. The site planning and selection problem for distribution centers includes the decisions of site location and distribution network flow. This problem was formulated as mixed-integer program with N-P hard property. Previous researches were focused on the "plant-distribution" or "distribution center-retail store" problem (ie. 2 levels). While this research was expanded to "plant-distribution center-retail store" problem (ie. 3 levels) with multiple products consideration. The problem was solved by simulated annealing approach (SA) as the results were compared with branch and bound approach. The results show that 1). The SA approach can provide acceptable solutions to this problem. 2). The factor of repeated both in time and cost.