Abstract: Based on observed data of radioactive isotope radon, this paper analyzes the characteristics of post-seismic effect of gas radon and water radon from the 12 May, 2008.Wenchuan 8.0 earthquake. The results show that the observation points which exhibit post-seismic effect of radon are mainly distributed in the north-east and south of epicenter along the earthquake rupture zone, and the variation style is mainly step-wise rising. Some observation points exhibit changes of water levels and flow possibly associated with radon changes. Up to October 2008, most observation points which showed post-seismic effect of radon have restored to the original values, however, there have still been a small number of points maintaining high or low value, and some points even continue to rise or fall. The statistical results confirms radon changes in response to seismic waves. We also put forward some scientific issues, such as the study of dynamic relationship between the chemical composition of groundwater and aquifer, which may useful to the study of the mechanism of earthquake precursors of radon.

Key words: Wenchuan earthquake, Radon, Post-seismic effect, Mechanism interpretation