The present invention provides a policy and charging rule generation method and system, relating to the field of communication technologies. One policy generation device controls service identification functions of multiple dedicated networks, so that the multiple dedicated networks share the same service identification rule library. The method comprises the steps that when a mobile terminal sends an attach request, a gateway device sends a policy and rule request to a policy generation device; the policy generation device generates multiple incomplete policy and charging rules according to service type parameters and status information of the mobile terminal, and sends the multiple incomplete policy and charging rules to the gateway device; the gateway device sends an inquire request to a service identification rule library device; the service identification rule library device searches data packet feature information of each application identifier and returns the data packet feature information of each application identifier to the gateway device; and the gateway device generates policy and charging rules. The method and system are applied to network control.