Abstract: Cloud storage technology is an important research area of cloud computing,because of the loss of privacy and security concerns,public cloud storage services are often difficult to be widely used in organizations which keep the core data,such as the innovative enterprises or the army．VI-PCS,a secure private cloud storage system based on virtual isolation mechanism,was proposed in which physical storage media and public cloud storage services are virtualized as storage capabilities,which are managed through centralized life-cycle,provide storage services for applications in VI-PCS；file storage procedure is divided into three levels(i.e．Meta-data management,virtual storage and physical stora-ge),in which secure,reliable data storage is achieved by file renaming and transparent encryption and decryption technology；a secure net disk based on isolated sandbox is provided as access method,and data security,controllability and availability are achieved in this isolated environment；a file bidirectional synchronization method based on ordered hash tree is proposed,and its offline mode is also helpful to improve system availability and adaptability．The results show that VI-PCS has certain advantages in reliability,security,scalability and adaptability.

Key words: Cloud computing,Private cloud storage,Virtual isolation,Sandbox,Bidirectional synchronization