Based on the literature review which concludes the Lean Six Sigma management theory, Information Technology Infrastructure Library (ITIL) and the key success factors of Information Technology service management (ITSM), this paper analyzes the present situation of information system in G bank and also the challenge it is facing. Furthermore, this paper puts forward a process optimization scheme for the production changes of G bank’s ITSM with the Lean Six Sigma management theory. What’s more, the paper dissects the production changes of G bank’s ITSM by means of DMAIC method in order to achieve these four goals: Firstly, optimizing the process and improving the internal work efficiency also. Secondly, reducing the variation and the error rate and also improving the system availability. Thirdly, strengthen the business interaction in order that the IT value could be reflected preferably. The last but not least, cutting the overtime is to improve employee satisfaction. But improving the ITSM of the banking industry is our ultimate aim.