This paper corrected complete Tangshan earthquake sequence data for long time, Based on the time-space epidemic-type aftershock sequence (ETAS) model and stochastic declustering method declustering on 1976 Tangshan earthquake sequence analyzed activity characteristics of long time, The result showed that Tangshan seismic region entering the late phase of the aftershock activity after 1992, now seismic activity has not yet been fully restored to the background seismicity level. With the frequency and strain energy of two different abnormal index analyzed the indicative significance of Tangshan seismic region as" Aftershock window" forecast the moderate and strong earthquakes, The result showed that  1980-1986 in the early stages of Tangshan “aftershock window”, frequency as abnormal index reflecting earthquake effect was better, 1992-2010 in the late stages, strain energy as the abnormal index reflecting earthquake effect was better.