The invention discloses a time synchronizing method and device. The method may comprise that local time and n time data points of clock offset are obtained, time offset represents difference between the local time and global networking time set by a root node, and n represents an integer greater than 1; the n time data points generate a regression relation which represents the relation between the local time and global networking time; and when time synchronization is needed, the local time is converted into the global networking time via the regression relation. According to the invention, under the condition that the time synchronizing precision is ensured, system resources occupied by time synchronization is reduced, and the system energy cost is reduced.