An expired backup processing method, wherein the method is performed by a backup server, and comprises: each time after an expired backup of first disk data is determined, creating a deletion log of the first disk data, and storing a pointer of invalid data in the expired backup into the deletion log, wherein the expired backup is an earliest backup in all unexpired backups of the first disk data that have been performed in an object-based storage system by a current first moment; detecting whether a deletion condition is met, and if the deletion condition is met, obtaining a plurality of deletion logs corresponding to the first disk data; determining, based on the plurality of deletion logs, a first target large object that is stored in the object-based storage system and that comprises valid data and the invalid data, wherein the first target large object includes a plurality of consecutive data blocks; generating (511, 610) at least one new large object identifier, wherein the at least one new large object identifier is in a one-to-one correspondence with at least one new large object, and wherein a quantity of to-be-created new large object identifiers is determined based on a quantity of pieces of the valid data in the at least one first large object that includes the invalid data and the valid data and a quantity of objects that actually can be stored in a large object; sending (611, 550, 570) a data migration indication and an object deletion indication to the object-based storage system, wherein the data migration indication is used to instruct the object-based storage system to migrate the valid data in the first target large object to the at least one new large object, and the object deletion indication is used to instruct the object-based storage system to delete the first target large object. each time after an expired backup of first disk data is determined, creating a deletion log of the first disk data, and storing a pointer of invalid data in the expired backup into the deletion log, wherein the expired backup is an earliest backup in all unexpired backups of the first disk data that have been performed in an object-based storage system by a current first moment; detecting whether a deletion condition is met, and if the deletion condition is met, obtaining a plurality of deletion logs corresponding to the first disk data; determining, based on the plurality of deletion logs, a first target large object that is stored in the object-based storage system and that comprises valid data and the invalid data, wherein the first target large object includes a plurality of consecutive data blocks; generating (511, 610) at least one new large object identifier, wherein the at least one new large object identifier is in a one-to-one correspondence with at least one new large object, and wherein a quantity of to-be-created new large object identifiers is determined based on a quantity of pieces of the valid data in the at least one first large object that includes the invalid data and the valid data and a quantity of objects that actually can be stored in a large object; sending (611, 550, 570) a data migration indication and an object deletion indication to the object-based storage system, wherein the data migration indication is used to instruct the object-based storage system to migrate the valid data in the first target large object to the at least one new large object, and the object deletion indication is used to instruct the object-based storage system to delete the first target large object.