A method for realizing application detection and control in an IP-Connectivity Access Network, IP-CAN, session supporting dual IP stack, comprising: obtaining an IPv4 address by User Equipment, UE, after the UE establishes an IP-CAN session and obtains an IPv6 address; the method further comprising: informing, by a Policy and Charging Rules Function entity, PCRF, a Traffic Detection Function, TDF of the IPv4 address via a TDF session corresponding to the IP-CAN session; and associating, by the TDF, the IPv4 address with the established TDF session; performing, by the TDF, application detection and control on traffic, of which a source address and/or a destination address is/are the IPv4 address, according to an Application Detection and Control, ADC, rule related to the TDF session; wherein informing, by the PCRF, the TDF of the IPv4 address via the TDF session corresponding to the IP-CAN session comprises: sending, by the PCEF, a message of indication of IP-CAN session modification to the PCRF, and making the message of indication of IP-CAN session modification carry an IP address allocation indicator and an IPv4 address; saving, by the PCRF, the IPv4 address carried in the message of indication of IP-CAN session modification and returning an acknowledgement message to the PCEF; sending, by the PCRF, a TDF session modification request to the TDF via the TDF session corresponding to the IP-CAN session, and making the TDF session modification request message carry the IP address allocation indicator and the IPv4 address. informing, by a Policy and Charging Rules Function entity, PCRF, a Traffic Detection Function, TDF of the IPv4 address via a TDF session corresponding to the IP-CAN session; and associating, by the TDF, the IPv4 address with the established TDF session; performing, by the TDF, application detection and control on traffic, of which a source address and/or a destination address is/are the IPv4 address, according to an Application Detection and Control, ADC, rule related to the TDF session; wherein informing, by the PCRF, the TDF of the IPv4 address via the TDF session corresponding to the IP-CAN session comprises: sending, by the PCEF, a message of indication of IP-CAN session modification to the PCRF, and making the message of indication of IP-CAN session modification carry an IP address allocation indicator and an IPv4 address; saving, by the PCRF, the IPv4 address carried in the message of indication of IP-CAN session modification and returning an acknowledgement message to the PCEF; sending, by the PCRF, a TDF session modification request to the TDF via the TDF session corresponding to the IP-CAN session, and making the TDF session modification request message carry the IP address allocation indicator and the IPv4 address. sending, by the PCEF, a message of indication of IP-CAN session modification to the PCRF, and making the message of indication of IP-CAN session modification carry an IP address allocation indicator and an IPv4 address; saving, by the PCRF, the IPv4 address carried in the message of indication of IP-CAN session modification and returning an acknowledgement message to the PCEF; sending, by the PCRF, a TDF session modification request to the TDF via the TDF session corresponding to the IP-CAN session, and making the TDF session modification request message carry the IP address allocation indicator and the IPv4 address.