A Logical Unit Number (LUN) division method and device includes checking and adjusting a connection manner and numbers of Serial Attached Small Computer System Interface (SCSI) (SAS) connections of storage enclosures and a controller, so as to make a maximum output bandwidth of each storage enclosure consistent (Si); querying controller port identifiers and storage enclosure identifiers (S2); creating a Mdisk array, and adding the corresponding controller port identifier and the corresponding storage enclosure identifier for each Mdisk (S3); logically dividing a storage space in the Mdisk array to create a volume, and dividing the volume into LUNs, whereby Mdisks that form the LUNs are made to come from different storage enclosures and different controller ports (S4); and mapping the LUNs to a host (S5).