The present invention provides an address allocation processing method, apparatus and system. The method includes: receiving, by a first BRAS, a DHCP relay packet sent by a second BRAS, wherein the DHCP relay packet includes a gateway IP address and source IP address-based response information; parsing, by the first BRAS, the DHCP relay packet, acquiring the gateway IP address, and allocating an idle IP address from an acquired address pool matching the gateway IP address; encapsulating, by the first BRAS, a source IP address in the DHCP relay packet into a destination IP address in a response packet according to the source IP address-based response information, and sending the idle IP address carried in the encapsulated response packet to the second BRAS. The present invention effectively solve a problem that an address waste phenomenon exists by using a built-in DHCP server in a dual-device hot backup scene.