Media stream sending method for both monitoring part in network video monitoring system

This invention discloses a method for monitoring both media stream transmission based on network video monitoring system, wherein network addresses of client and terminal video device are set as special addresses after NAT; the method comprises following steps: client and terminal video device transmits respective address information to SIP proxy of the network vide monitoring system via the NAT. SIP proxy transmits received address information from both monitoring parties to each other respectively, the terminal video device transmits detection information to network address of the client to determine connection capability, in order to carry out media stream transmission in P2P mode between subsequential two parties via established connection. Method according to this invention is suitable for various conditions when both monitoring parties are behind the NAT.