The invention provides a method to deal with the failures of proxy call session control function, a UE is provided with a host and a standby P-CSCF by an IMS network, the UE and an S-CSCF are used for storing the information of the host and the standby P-CSCF, when the S-CSCF sends service requests to the UE through the host P-CSCF, if the host P-CSCF is overtime and gives no response, the S-CSCFcan send indication to the UE through the standby P-CSCF to request the UE to carry out initial registration, if the host P-CSCF sends back wrong responses, the S-CSCF can send indication to the UE through the host or the standby P-CSCF to request the UE to begin the initial registration, the UE can verify whether the P-CSCF which retransmits the indication is the host or the standby P-CSCF or not , if the result is yes, the initial registration request can be sent to the P-CSCF, after the success of the initial registration, the S-CSCF can send the service request to the UE through the P-CSCF which retransmits the initial registration request.