Under globalization, many firms increasingly opt to blur their organizational boundaries to enhance the quality of both raw materials and final products. Manufacturers typically purchase components or parts from suppliers to manufacture products for customers. First-tier suppliers then purchase components from second-tier suppliers in a multi-layered sourcing supply chain. The quality of components or parts purchased from first and second tier suppliers affects the quality of finished products. In this paper, a quality model is proposed to ensure the yield rate of each tier (second-tier suppliers, first-tier suppliers and the manufacturer).