Abstract: This article introduces the practical observations of the pre-earthquake electromagnetic wave observation station network in Jiangsu region in resent years and discusses the electromagnetic wave warning-signs during the approaching period of earthquakes based on the observations of the electromagetic radiation signals before the Liyang earthquake Ms 6.0 in Jiangsu province in 1979, the Heze earthquake Ms 5.9 in Shandong province in 1983 and the South Yellow Sea earthquake Ms 6.2 in 1984.