1. A method for selecting policy decision functional entity in the resource and admission control system, comprising: receiving at a Transport Resource Control Function Entity (TRC-FE) a resource request message from a Customer Premises Equipment (CPE), or receiving at a Policy Enforcement Function Entity (PE-FE) a transport layer signaling sent by the CPE, for resource and admission control in PULL mode; determining, by the TRC-FE or the PE-FE, whether identification of a Policy Decision Functional Entity (PD-FE) that has provided authorization for the CPE has been stored in the TRC-FE or the PE-FE, when the TRC-FE or the PE-FE is interacting with more than one PD-FEs; selecting, by the TRC-FE or the PE-FE, the PD-FE that has provided authorization for the CPE when the identification information of the PD-FE has been stored; selecting, by the TRC-FE or the PE-FE, a statically configured PD-FE when no identification information of the PD-FE has been stored; and sending a resource decision request message from the TRC-FE or the PE-FE to the selected PD-FE.