A garbage collection technology for a storage medium that includes a plurality of blocks, where each storage unit has a collection parameter related to data in one of the blocks, and where each block includes a plurality of pages. A group of blocks is selected from the plurality of blocks based on the collection parameter. A difference between values of collection parameters of any two blocks in the group of blocks is not greater than a preset value. Data in a first valid page and a second valid page in the group of blocks is replicated to a same destination block, to facilitate garbage collection.