The disclosure provides a policy control method and a policy control system for accessing a fixed broadband access network. The policy control method includes: a FMC PF used for sensing the access of UE to a fixed broadband access network is set in a mobile network which a user requests to be accessed to; after the FMC PF receives a trigger message from an ePDG, the FMC PF requests a BPCF to establish a policy session, and the BPCF performs, policy control according to the information of the fixed broadband access network accessed by the UE. It can be seen from the method of the disclosure that when the UE is accessed to the 3GPP through the fixed broadband access network, the FMC PF senses a gateway control session establishment request message or a DHCP request message from the ePDG, so that a PCRF of the 3GPP access network accessed by the UE is triggered to send a policy session request to the BPCF. In this way, in the case that the fixed broadband access network fails to sense the access of the UE or that the fixed broadband access network does not support 3GPP-based access authentication in the conventional art where the UE is accessed to a 3GPP core network through the fixed broadband access network, QoS control is achieved for the access of the UE, and thus QoS guarantee is provided to the entire transmission path of data.