Example sleeping and wake-up methods and apparatuses of a master-slave network, and a power saving system of a master-slave network, are described. One example method includes obtaining running statuses of slave devices on links from a link management list. A target device is determined. 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, it is determined 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. A power saving message is sent 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.