1. A method for selecting policy decision functional entity in the resource and admission control system, comprising: a Transport Resource Control Function Entity (TRC-FE) or a Policy Enforcement Function Entity (PE-FE) selecting a Policy Decision Functional Entity (PD-FE) according to stored identification information of the PD-FE or according to statically configured PD-FE, if the TRC-FE or the PE-FE is interacting with more than one PD-FEs, after the TRC-FE receives a resource request message from a Customer Premises Equipment (CPE) or after the PE-FE receives a transport layer signaling sent by the CPE, for resource and admission control in PULL mode; and the TRC-FE or the PE-FE sending a resource decision request message to the selected PD-FE.