The invention provides a power grid emergency control method and device for dealing with the impact of DC faults on weak AC channels. The method includes the following steps: determining the total cut-off limit according to the total power loss of multiple DC lines after simultaneous locking faults and the total surplus power of weak AC channels; determining the additional cut-off quantity allocation coefficient of each DC line according to the minimum cut-off demand of the DC lines with simultaneous blocking faults; and determining the additional cut-off quantity of each DC line according tothe total cut-off limit and the additional cut-off quantity allocation coefficient of each DC line, and performing cut-off control. The technical scheme provided by the invention can take into accountboth the cut-off demand in case of a blocking fault of a single DC line and the cut-off demand in case of simultaneous blocking faults of multiple DC lines, and has good adaptability to multi-fault scenarios. The technical scheme has the advantages of being simple in principle, stable and reliable, and highly operable and practical, and has high practical value and good market prospects.