The present invention discloses a system and method for CSCF entity disaster tolerance and load balancing the system comprises P-CSCF entities, I-CSCF entities and S-CSCF entities, and further comprises a DNS Server. The present invention uses a DNS UPDATE message to report the load equivalent weight of the CSCF entity at regular time, so that the DNS Server can use the load equivalent weight when executing the load balancing strategy. It makes the disaster tolerance and load balancing in the IMS network be much easier to use and extend, thus reducing the load of the IMS network.