Sleeping and wake-up methods and apparatuses of a master-slave network, and a power saving system of a master-slave network, are provided. The method includes: obtaining, from a link management list, running statuses of slave devices on links; determining a target device, where the target device is a slave device whose running status is idle; if running statuses of the target slave device to an end slave device on a link on which the target slave device is located are all idle, determining that a sublink from the target slave device to the end slave device on the link on which the target slave device is located is a target sublink; and sending a power saving message to at least one slave device on the target sublink, so that the slave device enters a sleep and listen state when receiving the power saving message.