Abstract: In this paper, the authors described the seismic gap image before the 1668 Tancheng earthquake and the seismic gap image of modern East China, and found that they are very similar in that they are both around the Tanlu faulted zone, exhibit oval shape and have nearly NS-trending long axis. They occupy an area of about 39×10⁴km² covering Hebei, Henan, Shandong, Jiangsu, Anhui, Shanghai and the Yellow Sea. They are similar to each other in range, shape, area and formation time of the seismic empty region. In addition, since 2010, earthquake precursory anomaly has appeared in East China, which is located near the Tanlu faulted zone. The great earthquake risk probability along southern Tanlu zone is increasing, which is worthy of attention.