By analyzing historical strong earthquake activity，tectonic activity background， regional strain accumulation and anomaly character on regional seismicity before the Nilka-Gongliu MS6. 0 earthquake on November 1，2011 and the Xinyuan-Hejing MS6. 6 earthquake on June 30， 2012，the article researches the mid- and short-term anomaly character on seismicity before the two MS 6. 0 earthquakes． The result shows that moderately strong earthquake activity in the northern Tianshan mountains appeared accelerated since June，2011，and entered into the strain energy release stage． There are obvious mid-term anomalies such as MS6. 0 earthquake quiescence and broken，grouping activity and space migration of moderately strong earthquakes，seismic belt and gap etc． before the 2011 Nilka-Gongliu MS 6. 0 earthquake and the 2012 Xinyuan-Hejing MS6. 6 earthquake． There appeared M ＞ 4. 0 earthquake gap and imminent earthquake with the magnitude 5. 0 before the two earthquakes，and the time intervals between the imminent earthquakes and the mainshocks were both 14 days or so，and which shows the clear abnormal images and mid- and short-term anomaly character．