AbstractThe average statistical features of ETAS (Epidemic Type Aftershock Sequence) model parameters during the early stage (15 days) after the moderate or large earthquakes in Chinese mainland have been studied and the decay and generation of aftershocks under the different conditions have been discussed. Macroscopically, the numerical distribution of primary parameters of the ETAS model, b, p and α , are dispersed and the differences of the average value of parameters under different conditions are not very remarkable. In detail, b‐value increases with the magnitude of the mainshock, but the differences of b‐value are not obvious for different regions, for different mainshock fracture modes, as well as for different sequence types. p‐ and α ‐value show some regional features, average p‐values in southwest and northwest region of China are a little larger than that in Xinjiang and in North China, this means that the decay of aftershock activity is a little slower in southwest and in northwest region than in Xinjiang and in North China. Average α‐value is smaller in northwest region, and is larger in North China, which means that the earthquake in North China has a high ability to generate high‐order aftershocks, despite the aftershock decay in North China is something quick. And for northwest region of China, despite the aftershock decay is slow, due to the simplex framework of aftershock sequences, the ability of high‐order aftershock generation is something weak. It is not evident for a relation between p‐value and the fracture mode of the mainshock, in other words, the mainshock fracture mode is not the key factor controlling the aftershock decay rate. α‐value is related to the mainshock fracture mode to some extent. Averagely, α‐value is small for strike‐slip, middle for oblique slip, and large for dip slip. This expresses that the strike slip has the higher ability to generate aftershocks and it is weaker for dip slip and middle for oblique slip. p‐ and α‐value decreases with the increment of the mainshock magnitude, which means that the larger the mainshock, the slower the sequence decay and the higher the ability to generate offspring. There are some differences in p‐ and α‐values of different sequence types. p‐value is smaller for mainshock‐aftershock type (MAT) and is larger for isolated earthquake type (IET), expressing that aftershock decay rate is slow for MAT, is quick for IET and is in the middle for multiple mainshock type (MMT). α‐values of IET and MAT are about the same, both two are larger than that of MMT, this means that MMT has a higher ability to generate high‐order aftershocks than IET and MAT.