The invention discloses a method for acquiring the state of a hard disk out of band, including a remote host, BMC, Expander and a hard disk, wherein the remote host accesses the BMC through a LAN or Serial interface, the Expander connects to the hard disk through sas and sata, and the BMC and the Expander physically pass through I2C connection, IPMB protocol is used for data communication. When requesting data, BMC performs Write operation as Master, and Expander performs Read operation as Slave; when data is returned, Expander performs Write operation as Master, and BMC performs Read operation as Slave. Physically connect the Expander to the BMC through I2C, a commonly used communication method, to transmit the status of the hard disk, and then perform effective remote monitoring through the BMC, providing a method for remote / out-of-band monitoring of the operating status of the hard disk.