A connection establishment method, a communication apparatus, and a system which are applied to a terminal device connected to an edge network. The method includes a core network element sending first information to at least one control network element, where the first information indicates that an edge network corresponding to a user plane network element serving the terminal device changes. The at least one control network element sends connection information of a first network element to the terminal device based on the first information, where the first network element is a network element in a first edge network corresponding to the user plane network element. After receiving the connection information of the first network element, and the connection information is used for the terminal device to connect to the first network element.