A first network slice selection network element sends a synchronization request message to a second network slice selection network element, where the synchronization request message includes an identifier of an access management network element and slice availability information of the access management network element; the first network slice selection network element receives a task deletion message from the second network slice selection network element, where the task deletion message includes the identifier of the access management network element or a task identifier of a first subscription task, and the first subscription task is a subscription task that is for the slice availability information of the access management network element and that is created in the first network slice selection network element; and the first network slice selection network element deletes the first subscription task.