Building method of safe connection among user terminals and system thereof

The invention provides a building method of safe connection among user terminals, comprising the following steps: 1) a first user terminal STA1 transmits an inter-station secret key request packet to switching equipment SW; 2) after receiving the inter-station secret key request packet transmitted by the first user terminal STA1, the switching equipment SW generates an inter-station secret key, an inter-station secret key announcement packet is constructed and is transmitted to a second user terminal STA2; 3) after the second user terminal STA2 receives the inter-station secret key announcement packet transmitted by the switching equipment SW, an inter-station secret key announcement response packet is constructed and is transmitted to the switching equipment SW; the invention provides a building method of safe connection among user terminals and a system, by adopting the switching equipment, the inter-station secret key is built between the two user terminals which are connected directly to protect the confidentiality and integrality of user data among the user terminals.