The invention relates to a filter-based electromagnetic transient state simulation method and system. The method comprises, through a group of simulative filter circuits, simulating a plurality of groups of LCC (leadless chip carrier) converter station alternate current filters of the same kind to the simulative filter circuits, and through a parameter setting method, simulating the switch operation of the LCC converter station alternate current filters, wherein the parameter setting method is a method in which the electromagnetic transient state equivalent computing circuit of the filter circuits in real time corrects a historical current source. By compressing a dozen of alternate current filters of a practical LCC converter station into a plurality of types for simulation in an electromagnetic transient state program, the filter-based electromagnetic transient state simulation method and system can greatly reduce the number of electrical nodes and elements of a direct current powertransmission electromagnetic model, accelerate simulative models, and meanwhile have no loss in the filtering effects of the filters or the simulation precision of dynamic switching processes, therebyhaving high practical promotion values.