An address assignment method for a mobile communications system, wherein the method is applied to a terminal device, and comprises: receiving an address assignment request of a first device, wherein the address assignment request of the first device comprises access point information of the first device; parsing the access point information and obtaining an access point name of the first device based on the access point information of the first device; encapsulating the access point name of the first device into a first connection request; sending the first connection request to a packet core network device, wherein the first connection request is used to establish a first packet data network, further referred as first PDN, connection; receiving a first IP address assigned by the packet core network device in the first PDN connection; assigning the first IP address to the first device; after assigning the first IP address to the first device, receiving an address assignment request of a second device, wherein the address assignment request of the second device is used to request a second IP address; sending a second connection request to the packet core network device, wherein the second connection request is used to establish a second PDN connection; receiving the second IP address; and assigning the second IP address to the second device; characterized in that the second connection request carries an access point name of the second device; the access point name of the second device is used to identify a requested service type; the second IP address is assigned by the packet core network device in the second PDN connection based on the access point name of the second device; the address assignment request of the second device further comprises access point information of the second device; and the method further comprises obtaining the access point name of the second device based on the access point information of the second device. receiving an address assignment request of a first device, wherein the address assignment request of the first device comprises access point information of the first device; parsing the access point information and obtaining an access point name of the first device based on the access point information of the first device; encapsulating the access point name of the first device into a first connection request; sending the first connection request to a packet core network device, wherein the first connection request is used to establish a first packet data network, further referred as first PDN, connection; receiving a first IP address assigned by the packet core network device in the first PDN connection; assigning the first IP address to the first device; after assigning the first IP address to the first device, receiving an address assignment request of a second device, wherein the address assignment request of the second device is used to request a second IP address; sending a second connection request to the packet core network device, wherein the second connection request is used to establish a second PDN connection; receiving the second IP address; and assigning the second IP address to the second device; characterized in that the second connection request carries an access point name of the second device; the access point name of the second device is used to identify a requested service type; the second IP address is assigned by the packet core network device in the second PDN connection based on the access point name of the second device; the address assignment request of the second device further comprises access point information of the second device; and the method further comprises obtaining the access point name of the second device based on the access point information of the second device.