A downlink data notification message sending method and apparatus are disclosed. In an embodiment a method includes receiving, a delay instruction from a mobility management network element, which is used to instruct a control plane network element to delay sending a DDN message, receiving, an event report message includes a reported event from a user plane network element, and the reported event is used to notify the control plane network element that a downlink data packet sent to UE matches no bearer, determining, that the UE is registered in the mobility management network element, and if the control plane network element has not received, within a first time period, routing information of a base station, sending, the DDN message to the mobility management network element when the first time period expires.