As a result of adopting Six Sigma, many companies equipped with mass production system seem to get more financial effects in these days. In some cases with small volume high variety production system, however, it is not easy to apply Six Sigma properly and to find some financial results as well. In this study, we reviewed the deployment process of Six Sigma and characterized each development step, for one of the major Korean companies with small volume high variety production system. To enhance the short term cash flow, the project-based improvement strategy can be replaced by the whole process optimization and the reducing efforts of opportunity costs as well as COPQ (cost of poor quality). This approach is now applied to all functions of the company, including strategic planning, sales, R&D, production, quality assurance, purchasing, and management support. Furthermore, a sustainable Six Sigma growth strategy is suggested for the companies with small volume high variety production system.