The invention relates to an emergency power support control method for an alternating-current grid partition interconnection device. The method comprises the steps of: setting a normal operation control strategy of the partition interconnection device, i.e., according to the load flow of the partition interconnection device in normal operation, classifying one converter connected with the sending end of the device as an I-class controller, and classifying all remaining converters as II-class controllers; setting a control value of emergency power control of the partition interconnection device; detecting an alternating-current grid voltage frequency f, and setting an active power control method for the II-class controllers; detecting an alternating-current grid voltage amplitude uac, and setting a reactive power control method for the II-class controllers. By adopting the technical solution, emergency power support without inter-station communication is realized, and the technical problem that the existing control strategy cannot timely and effectively meet the requirement of emergency power support is solved.