This application provides a hard disk format conversion method and apparatus, and a storage device, and belongs to the field of storage technologies. In this application, a storage format of a storage unit is converted from an SMR format to a PMR format. Because IOPS in the PMR format is higher than IOPS in the SMR format, IOPS in the storage unit can be increased after the storage format is converted. Alternatively, a storage format of a storage unit is converted from the PMR format to the SMR format. Because a storage capacity in the SMR format is higher than a storage capacity in the PMR format, a storage capacity of the storage unit can be increased after the storage format is converted.