A data deduplication method and apparatus are provided. The method includes receiving an overwrite request sent by an external device, where the overwrite request carries a data block and a first address into which the data block is to be stored; determining whether an overwrite quantity of the first address exceeds a first threshold within a time period [t1, t2], where both t1 and t2 are time points, and t2 is later than t1; and when the overwrite quantity of the first address exceeds the first threshold within the time period [t1, t2], skipping performing a deduplication operation on the data block; or when the overwrite quantity of the first address does not exceed the first threshold within the time period [t1, t2], performing a deduplication operation on the data block. Therefore, a large quantity of computing resources of a storage server are saved, and impact brought by a deduplication operation on storage server performance is also decreased.