Mass customization is one of the leading strategies in satisfying customers and assuring companies survival in today’s markets. From the point of view of lifecycle management, it includes knowledge of customer requirement, customer preference, raw material purchasing, customization manufacturing process, product price which reflects satisfaction of both sides of bargain. This paper proposes a knowledge management model in E-commerce mass customization, which is consisted of three parts: the customer information gathering model, the purchasing and manufacturing model and the pricing model. The modeling process and further analysis show that the model efficiently integrates different knowledge in mass customization lifecycle and can serve as a useful platform in E-commerce.