Embodiments of the invention provide a method and device for coordinating parallel calculation in electric power systems, relates to the technical field of electric power systems, and aims at improving the speed of simulating calculation in the electric power systems. The method comprises the following steps of: dividing an electric power system network into K non-overlapped sub-networks, wherein K is a positive integer greater than or equal to 2; selecting m cutting branches and s fault branches from the K sub-networks, wherein both m and s are positive integers greater than or equal to 1, the cutting branches are formed by two nodes with electric connection relationship in any two sub-networks in the K sub-networks, and the fault branches are formed by two nodes with short circuit in each sub-network; and calculating a three-sequence admittance matrix and a three-sequence injection current matrix of the m cutting branches, and a three-sequence admittance matrix and a three-sequence injection current matrix of the s fault branches in parallel. The method and device provided by the invention are applied in the electric power system network.