The invention provides a method for a dynamical virtual a private network, which is suitable for a main device in a dynamic virtual private network. The method comprises: (a) before the main device establishes a tunneling connection, acquiring a request for adding a sub-device to a whitelist directly or through a third-party cloud service and sending an acceptance message or a rejection message to the sub-device accordingly thereto; (b) acquiring a request for connecting with the sub-device directly or through the third-party cloud service, and determining whether the tunneling connection with the sub-device is established or not accordingly thereto or sending a rejection message to the sub-device; (c) after the tunneling connection is established between the main device and the sub-device, receiving a connection code sent from the sub-device through the tunneling connection, and determining whether the connection code sent from the sub-device is correct or not.