Abstract: Introduction At present the public cloud service develops rapidly, many companies also begin experimenting with the public cloud service, try to migrate and deploy their information systems on public clouds. Method The practical experiences in nearly four years were studied for China Energy Construction Co., Ltd. Result The paper elaborates and summarizes the deployment methods and safety protection measures of public cloud service, and develps a set of scientific and practical methods. Conclusion This work provides some guidance for further study on how to do well in login of information system, especially when application system deployed on public cloud.