This application provides a packet sending method, applied to a communications system including at least two nodes, the at least two nodes include at least one parent node having a child node, a packet sent by the child node is forwarded by the parent node, and the method includes: receiving, by a first node, first instruction information, where the first instruction information is used to instruct the first node to send a packet after a first moment, and the first node is a parent node; and sending, by the first node, a first packet according to the first instruction information.