A serious conflict problem of the native IP addresses appears in the largescale applications of the VPN system, which leads to a new compatibility problem of network configuration that only modifies the  compatible native IP address. This paper analyses the effect of the conflict problem that different hosts use the same native IP address and gives a scheme of using the virtual network card address to flag the IPSec policy in a virtual private network, and presents a new Windows VPN architecture applying a virtual network card which can resolve the native IP address conflict problem well and bring about new characteristics of a VPN application.