Abstract: A preliminary discussion is made on application of gasg eochemical method to prediction of seismic trend af ter Shunyi 4.5 earthquake. The research result indicates that Hg content in soil gas in the epicent ral area was rapidly decreased. CH4 is the main component of the escaping gas discharged f rom the anomalous site in Longqing xia reservoir, Yanqing County. It is mainly originated from biog enic reaction but not an earthquake precursor anomaly. According to the abov e result, it is sugg ested that the tectonic activity lev el is not turn to streng then in the circum-Capital area af ter Shunyi 4.5 earthquake. Therefore, on December 17, 1996, it was predicated that an earthquake of MS≥5.0 was less possible to occur in 15 days in the circum-capital area.

Key words: Gas geochemistry, Seismic trend after main shock, Shunyi earthquake, Circum-Capital area