A data deduplication 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.