This article presents a six sigma project for improving purchase conversion rate in mobile game site. The project was carried out based on DMAIC process. First, a defect rate is defined as low purchase conversion rate. In addition, 60-days purchase data was analyzed and it is shown that the defects level was 2.48 sigma level. In this study, in order to raise the sigma level, six personalization services were used in the mobile game site. Six factors were determined based on FDPM(Functional Deployment Process Map), fishbone chart, linear regression analysis, effort-performance matrix, and so on. The sigma level of defects has improved from 2.48 to 2.93.