The invention discloses a policy and charging control method, system and device. The method comprises the following steps: after a credit control request requesting policy and charging relevant rule information sent by a policy and control enforcement function device is received, judging whether or not a policy and charging control (PCC) rule needs to be enabled for a user; if so, issuing a credit control response carrying the policy and charging relevant rule information to the policy and control enforcement function device; and otherwise, issuing a credit control response giving an instruction for closing a Gx interface session to the policy and control enforcement function device. The invention also discloses a device and system for implementing the method.