Abstract: In this paper, the tempo-spatial distribution of strong earthquake since 1895 in Tianshan block has been studies. The results show that: ① All earthquakes with M_S≥7.0 occurred along the boundary zones of the Tianshan block. The seismic activity along southern boundary zone is higher than that along the northern one, and the seismicity of their west is higher than that of their east. While there exists the highest seismic activity and has complicated earthquake sequences along the western segment of the South Tianshan. ② It is obviously that the time distribution of strong earthquakes has quasi-periodic characteristics. The prominent period calculated by the maximum entropy spectral method is 40 years. The cycle coefficient of 40 years obtained by wavelet transform shows that M_S≥7.0 earthquakes occurred in the descend process of the cycle coefficient of 40 years period, and the quiet period is during the increase process of this cycle coefficient. ③ During seismic active periods and quiet periods, the space distribution of the activity of earthquakes with M_S≥5.0 is different in different parts of Tianshan block, for example, the southern boundary of the block, the northern boundary of the block and the interior of the blocks. Especially in active period, the activity difference is smaller between the Southern boundary and the Northern boundary, but the difference between boundaries and the interior of the block is obvious. On the other hand, in quiet period, their difference is small. Meanwhile the seismic activity in the interior of the blocks is very strong. ④ In the activity period, there exists a corresponding relation of seismic activity between the southern boundary zone and the northern boundary zone. That is, if a strong earthquake occurs along one boundary zone, there will occur strong earthquakes along another zone in days or several years.

Key words: Active block, Quasi-periodic characteristics, Active period, quiet period, Maximum entropy spectral method, Method of wavelet transform