A method for implementing emergency call override service, wherein the method comprises: receiving (S501), by a second Service Call Session Control Function, S-CSCF, entity on a calling side, an initial request message from a calling party, the initial request message carrying an emergency call override service code and a called party number information in "Requestline" header of the initial request message; sending (S502), by the second S-CSCF entity, the initial request message carrying the emergency call override service code and the called party number information to a second Application Server, AS, on the calling side; in the case that the emergency call override service code in the "Requestline" header is determined to be matched with a pre-allocated emergency call override service access code and the calling party subscribes an emergency call override service, deleting (S503), by the second AS, the emergency call override service code in the "Requestline" header of the initial request message, setting, by the second AS, a service identifier indicating the emergency call override service into the initial request message, and sending (S504), by the second AS, the initial request message carrying the service identifier to the second S-CSCF entity; sending (S505), by the second S-CSCF entity, the initial request message carrying the service identifier to a first S-CSCF entity on a called side; sending (S506), by the first S-CSCF entity, the initial request message carrying the service identifier to a first AS on the called side; and implementing, by the first AS, the emergency call override service according to the service identifier. receiving (S501), by a second Service Call Session Control Function, S-CSCF, entity on a calling side, an initial request message from a calling party, the initial request message carrying an emergency call override service code and a called party number information in "Requestline" header of the initial request message; sending (S502), by the second S-CSCF entity, the initial request message carrying the emergency call override service code and the called party number information to a second Application Server, AS, on the calling side; in the case that the emergency call override service code in the "Requestline" header is determined to be matched with a pre-allocated emergency call override service access code and the calling party subscribes an emergency call override service, deleting (S503), by the second AS, the emergency call override service code in the "Requestline" header of the initial request message, setting, by the second AS, a service identifier indicating the emergency call override service into the initial request message, and sending (S504), by the second AS, the initial request message carrying the service identifier to the second S-CSCF entity; sending (S505), by the second S-CSCF entity, the initial request message carrying the service identifier to a first S-CSCF entity on a called side; sending (S506), by the first S-CSCF entity, the initial request message carrying the service identifier to a first AS on the called side; and implementing, by the first AS, the emergency call override service according to the service identifier. <EOS>