Embodiments of the present disclosure disclose a service processing method, a PCRF, and a system. The method performed by the PCRF includes: obtaining service information of a service, where the service information includes a service identity; obtaining, according to user information and the service information, information indicating that the service requires QoS guarantee, and service chain information; when determining, according to the service chain information, that a network resource occupied by the service may be changed, sending the service identity and the information indicating that the service requires the QoS guarantee to a value-added service processor; receiving target service information, returned by the value-added service processor, of the service corresponding to the service identity; generating a first control policy according to the target service information; and sending the first control policy to a PCEF, so that the PCEF reserves a first network resource according to the first control policy.