A data migration method, wherein the method is applied to a storage system, the storage system comprises a disk group, and the disk group comprises multiple solid-state disks SSDs, wherein each of the SSDs is divided into fine-grained chunks of a same size; and the method comprises: monitoring a size of bad blocks in each SSD in the disk group; determining a source SSD in the disk group of which a size of bad blocks exceeds a preset threshold, wherein a capacity usage ratio of the source SSD that is associated with the size of bad blocks of the source SSD is greater than an average capacity usage ratio of the disk group, wherein the capacity usage ratio of the source SSD is a ratio of a used capacity of the source SSD to an available physical capacity of the source SSD, and wherein the average capacity usage ratio of the disk group is a ratio of a used capacity of the disk group to an available physical capacity of the disk group; selecting one or more destination SSDs from the multiple SSDs with a capacity usage ratio less than the average capacity usage ratio of the disk group; obtaining a difference value between the capacity usage ratio of the source SSD and the average capacity usage ratio; multiplying the difference value between the capacity usage ratio of the source SSD and the average capacity usage ratio by an available physical capacity of the source SSD to obtain an amount of the data to be migrated from the source SSD; obtaining a number of chunks to be migrated from the source SSD by dividing the amount of the to be migrated from the source SSD by a size of a chunk, wherein the number of chunks to be migrated is greater than 1; migrating data to be migrated from the source SSD to the one or more destination SSDs according to the number of chunks to be migrated from the source SSD, wherein the data to be migrated is migrated in a unit of chunk. monitoring a size of bad blocks in each SSD in the disk group; determining a source SSD in the disk group of which a size of bad blocks exceeds a preset threshold, wherein a capacity usage ratio of the source SSD that is associated with the size of bad blocks of the source SSD is greater than an average capacity usage ratio of the disk group, wherein the capacity usage ratio of the source SSD is a ratio of a used capacity of the source SSD to an available physical capacity of the source SSD, and wherein the average capacity usage ratio of the disk group is a ratio of a used capacity of the disk group to an available physical capacity of the disk group; selecting one or more destination SSDs from the multiple SSDs with a capacity usage ratio less than the average capacity usage ratio of the disk group; obtaining a difference value between the capacity usage ratio of the source SSD and the average capacity usage ratio; multiplying the difference value between the capacity usage ratio of the source SSD and the average capacity usage ratio by an available physical capacity of the source SSD to obtain an amount of the data to be migrated from the source SSD; obtaining a number of chunks to be migrated from the source SSD by dividing the amount of the to be migrated from the source SSD by a size of a chunk, wherein the number of chunks to be migrated is greater than 1; migrating data to be migrated from the source SSD to the one or more destination SSDs according to the number of chunks to be migrated from the source SSD, wherein the data to be migrated is migrated in a unit of chunk.