Abstract: Based on the view that the earthquake in a block is subjected to the earthquakes occurred on the margin of the block, the seismicity in Hanzhong and Ankang basin is analyzed.The conclusions are:(1) the level of seismicity in downfaulted basin of a block is lower than that on the boundary of the block;(2) the seismic activity within the basin is mainly influenced by the bigger events occurred on the margin, which reflects the tectonic adjustment near the boundary after the occurrence of strong earthquakes;(3) when a big earthquake occurred in the interface near a basin, the seismic risk in the basin should be cautioned.