Seismologists are interested in the linear structure and neted tectonic framework and their relations to seismicity from the remote sensing images, but do not pay enough attention to seismicity. The circular structure is a kind of particular tectonic pattern showing on the sensing images. By using the remote sensing, author has analysed seismo-tectonic environment in the northwestern region of China for several years. About the action of circular structure on study of earthquakes, some points of view are presented in the following.