An event subscription method, comprising: receiving, by a user data management network element, a first message, wherein the first message is used for subscribing to a first event, the first message comprises a first time parameter and a type of the first event, and the type of the first event is used to indicate an event type of the first event; determining, by the user data management network element, duration of a subscribed periodic update timer of user equipment based on the first time parameter; sending (S 1205), by the user data management network element, the duration of the subscribed periodic update timer of the UE and the type of the first event to a mobility management function network element; receiving, by the user data management network element, a second message, wherein the second message is used for subscribing to a second event, the second message comprises a type of the second event and a second time parameter, and the type of the second event is used to indicate an event type of the second event; if the second time parameter is less than the duration of the subscribed periodic update timer of the UE, determining, by the user data management network element, updated duration of the subscribed periodic update timer of the UE based on the second time parameter; and if the type of the second event is a UE reachability event, sending, by the user data management network element, event parameter information to the mobility management function network element, wherein the event parameter information comprises the type of the second event and the updated duration of the subscribed periodic update timer of the UE. receiving, by a user data management network element, a first message, wherein the first message is used for subscribing to a first event, the first message comprises a first time parameter and a type of the first event, and the type of the first event is used to indicate an event type of the first event; determining, by the user data management network element, duration of a subscribed periodic update timer of user equipment based on the first time parameter; sending (S 1205), by the user data management network element, the duration of the subscribed periodic update timer of the UE and the type of the first event to a mobility management function network element; receiving, by the user data management network element, a second message, wherein the second message is used for subscribing to a second event, the second message comprises a type of the second event and a second time parameter, and the type of the second event is used to indicate an event type of the second event; if the second time parameter is less than the duration of the subscribed periodic update timer of the UE, determining, by the user data management network element, updated duration of the subscribed periodic update timer of the UE based on the second time parameter; and if the type of the second event is a UE reachability event, sending, by the user data management network element, event parameter information to the mobility management function network element, wherein the event parameter information comprises the type of the second event and the updated duration of the subscribed periodic update timer of the UE.