Because of the advance of technology and the popularization of network device construction, more and more information delivered by the Internet. And so the number of Cloud Services increased rapidly. To ensure the integrity of user data while providing services, the system should store backup data on remote storage systems. And we can improve the data reliability and recovery ability by improving the efficiency of synchronization processing. In this paper, we propose a solution based on dividing a file into flexible size blocks. When the file modified, we can judge each block is changed or not by utilizing pattern matching algorithm, and only need to update those changed blocks into backup storage systems after matching. So we can lower the transmission cost and increase the efficiency of the whole backup processing by reducing the amount of data we need to transmit.