Abstract: Based on the new magnetic data in the East China Sea, the characteristics of magnetic anomalies have been analyzed,magnetic basement been calculated and the features of basement and geology also analyzed. The magnetic anomalies change differently from west to east. From land to shelf and to the middle of the Okinawa Trough, the magnetic anomalies change between positive and negative, the highest negative magnetic anomaly also arises in Fujian coastal area and magnetic basement of this area changes between 5 km and 11 km. From the middle of Okinawa Trough to Ryukyu Islands arc, magnetic anomalies change from positive to negative and the magnetic basement of this area changes between 7 km and 12 km. From Ryukyu fore-arc basin to Ryukyu Trench, magnetic anomalies change between positive and negative and it is positive in the middle and negative in the two sides of this area and the magnetic basement changes between 7.5 km and 11 km.