Abstract: Fast synchronization of remote files is the basic technology for mobile cloud download, Web mirroring, remote system backup and other network scenarios. At present, the rsync algorithm proposed by Andrew Tridgell is widely used in Linux operating system. This paper proposes a new pre-compressed file synchronization mechanism for mobile cloud download. By introducing cache and information reuse at the terminal, it can significantly reduce the terminal computation and reduce the network bandwidth requirement. The results show that the improved algorithm based on rsync can simplify the calculation and significantly reduce the amount of data transferred through information reuse and caching, especially suitable for remote file synchronization occasions such as mobile cloud download which is sensitive to energy consumption.