A method for determining a policy and charging rule function entity, PCRF, comprising: receiving, by a second PCRF, a second request message carrying an IP address of a user transmitted by a second routing agent device; wherein the second PCRF is determined by the second routing agent device after receiving the second request message which carries a user identity of the user and the IP address of the user and is transmitted by a policy and charging enforcement function entity, PCEF, and wherein the second PCRF is determined by the second routing agent device by performing static configuration according to the user identity of the user, or according to a polling method or according to a load sharing proportion of each PCRF; transmitting, by the second PCRF, a corresponding relationship between the IP address of the user and the identity of the second PCRF to a first PCRF or a subscription profile repository, SPR, after the second request message carrying the IP address of the user is received; wherein a first routing agent device and the second routing agent device are the same routing agent device, or the first routing agent device and the second routing agent device are different routing agent devices; receiving, by the first PCRF, a first request message transmitted by the first routing agent device, wherein the first request message carries the IP address of the user; inquiring, by the first PCRF according to the IP address of the user, the corresponding relationship between the IP address of the user and an identity of a PCRF currently serving the user in the first PCRF itself or in the SPR and determining, based on the corresponding response to the inquiring received from either the first PCRF itself or from the SPR, that the identity of the PCRF currently serving the user is an identity of the second PCRF currently serving the user; and transmitting, by the first PCRF, a third message carrying the identity of the second PCRF to the first routing agent device, so that the first routing agent device transmits the first request message to the second PCRF according to the identity of the second PCRF. receiving, by a second PCRF, a second request message carrying an IP address of a user transmitted by a second routing agent device; wherein the second PCRF is determined by the second routing agent device after receiving the second request message which carries a user identity of the user and the IP address of the user and is transmitted by a policy and charging enforcement function entity, PCEF, and wherein the second PCRF is determined by the second routing agent device by performing static configuration according to the user identity of the user, or according to a polling method or according to a load sharing proportion of each PCRF; transmitting, by the second PCRF, a corresponding relationship between the IP address of the user and the identity of the second PCRF to a first PCRF or a subscription profile repository, SPR, after the second request message carrying the IP address of the user is received; wherein a first routing agent device and the second routing agent device are the same routing agent device, or the first routing agent device and the second routing agent device are different routing agent devices; receiving, by the first PCRF, a first request message transmitted by the first routing agent device, wherein the first request message carries the IP address of the user; inquiring, by the first PCRF according to the IP address of the user, the corresponding relationship between the IP address of the user and an identity of a PCRF currently serving the user in the first PCRF itself or in the SPR and determining, based on the corresponding response to the inquiring received from either the first PCRF itself or from the SPR, that the identity of the PCRF currently serving the user is an identity of the second PCRF currently serving the user; and transmitting, by the first PCRF, a third message carrying the identity of the second PCRF to the first routing agent device, so that the first routing agent device transmits the first request message to the second PCRF according to the identity of the second PCRF.