Customer service is one of the most important ingredients of the marketing mix for products and services. High quality customer service helps to create customer loyalty. A company would quickly lose business to competitors if under estimating the power of services. Therefore, the service management becomes more focus in foundry business. TSMC is the largest pure foundry service company with 50% of market share in foundry business. Customer partnership service is one of the core competences of TSMC. Long- term partnership is what TSMC treats customers and it¡¦s achieved by the win-win service strategy. There is a fewer paper to study the customer service in semiconductor foundry filed. This thesis is to study customer service strategy of TSMC. Why do chip design companies select TSMC as their major foundry source.