Embodiments of the present invention provide a method, an apparatus, and a system for determining a policy and charging rule function entity. The method includes: receiving, by a first PCRF, a first request message transmitted by a first routing agent device, where the first request message carries an IP address of a user; inquiring a pre-stored corresponding relationship between the IP address of the user and an identity of a PCRF currently serving the user according to the IP address of the user, and determining an identity of a second PCRF currently serving the user; and transmitting a message carrying the identity of the second PCRF to the first routing agent device. The method realizes that session information of the same user can be routed to the same PCRF when a biplane DRA is under a multi-PCRF networking, and provides reliable DRA signaling network networking.