Eastern mainland China is an earthquake-prone region with large population density and high level of national economic development. According to the difference of geological structure background and earthquake activities,eastern mainland China is divided into four regions,including Northeast China,North China,Southeast China coastal area and other areas of South China. We applied M_S ≥ 6.0 earthquake catalogue(deep earthquakes in Northeast China are not incorporated)to investigate the activity characteristics of the earthquakes in eastern mainland China. In this study,we discussed divisions of seismicity regions in eastern mainland China based on active-tectonic block theory,and then analyzed the seismic episode characteristics of strong earthquake activity distributions from time and space. Finally we evaluated the earthquake occurrence probability in future. Our main results suggest ①Earthquakes of M_S ≥ 6.0 in eastern mainland China are mainly concentrated in North China and Southeast coastal area,and other areas are with lower earthquake activity level. Meanwhile,earthquake activities of North China and Southeast coastal area are synchronic. ②The major regions of M_S ≥ 6.0 earthquakes in North China are concentrated in North China Plain block,Ludong-Huanghai block and Yanshan-Bohai seismic zone,and the major regions of M_S ≥ 6.0 earthquakes in Southeast coastal area are concentrated in Binhai(littoral) fault belt,Changle-Zhaoan fractured zone and Taiwan strait;In addition,the major regions of M_S ≥ 6.0 earthquakes in Northeast China are concentrated in Songliao Basin. ③By using the Weilbull distribution function fitting time intervals between first and second M_S ≥ 6.0 earthquakes happened in eastern mainland China from 1815 during the seismic active periods,we found that the probability of the M_S ≥ 6.0 earthquake within 5 years is relatively great.