Updates discovery is the key problem of data synchronization; it has been used to generate updates operations. The traditional algorithms ignore the modify semanteme, cause the updates operations increased. A new file updating discovery algorithm that supports semantic synchronization is proposed in this paper. The algorithm takes advantage of semantic info, which preserved in file system journal, to accurately recognize users originally modify intents. We take the NTFS file system as an example to realize and test the new algorithm. By comparison, the algorithm effectively reduces synchronization requests. Experiments show that, the algorithm cans timely respond to users’ modification and support massive file changes that occurred in short time. The algorithm is designed based on the basic features of file system journal, and can be applied to other file systems.