Embodiments of the present invention provide an IP address allocation system and method, which implement, if a control plane is separated from a forwarding plane, a function that enables user equipment to acquire an internet protocol (IP) address in a dynamic host configuration protocol (DHCP) manner. The method includes: receiving, by a forwarder, an address request sent by an external network element, where the address request includes a DHCP request of user equipment UE and user characteristic information of the UE; acquiring, from a DHCP service network element according to the DHCP request, an IP address allocated to the UE; and acquiring first instruction information that is delivered by a control device according to the user characteristic information of the UE and the IP address allocated to the UE, and sending the IP address to the UE according to the user characteristic information.