Providing good quality products and services is at the heart of customer satisfaction. Six sigma provides an effective mechanism to focus on customer requirements, through the improvement of process quality. This paper describes the application of the six sigma on assembly line management and proposed a method of six sigma Implementation efficiently. The essence of this paper is to design on how to find work defects in the assembly lines based on the implementation of DPO(defects per opportunity). This paper also proposes a managerial model of maintaining of job standards and finding and feedback of defects of products during working time. Finally this paper shows the validity of the proposed model through an empirical study.