Abstract: This paper deals with tectonic features and seismicity for the Tancheng-Lujiang fault belt in terms of aeromagnetic data.Some hidden segments of this fault belt,south of Tancheng,are discussed by use of aeromagnetic data in large and moderate scale. The Changyi-Daidian fault and An-qiu-Juxian fault are considered to be a main fault on the studied fault and they have extended down to the upper mantle.The author tries to find out the law for strong seismic activity. It may provide another base for modifying the location of the epicenter of 1668 earthquake of magnitude 8.5.