Data stream transmission method, device and equipment based on dual data network system

The invention provides a data stream transmission method, device and equipment based on a dual-data network system. The dual-data network system comprises a first network system and a second network system, and the method comprises the following steps: in a state that terminal equipment is connected with the first network system, the terminal equipment generates a first connection request in response to an updating instruction sent by a public user plane network element, and sends the first connection request to a control plane network element; the control plane network element connects the terminal equipment with an edge user plane network element in a second network system based on the first connection request; and if the connection between the terminal equipment and the edge user plane network element in the second network system is successful, the terminal equipment sets the effective connection duration of the second network system as a first preset duration, sends a first downloading update request to t