The present invention provides an electric power information network safety linkage defense method and system. The method comprises: collecting safety alarm data and performing preprocessing; employing a known attack mode to perform correlation analysis of the safety alarm data; performing sequence excavation of the safety alarm data; combining the network topology to automatically determine a network safety device participating in the linkage defense; and issuing the defense rule to the selected network safety device to realize linkage defense. The difficulty is solved that the electric power information network is difficult to defense the complex network attack.