Abstract: To investigate the characteristics of various earthquake sequences, we fitted three aftershock sequences of the March 21, 2008 M_S7.3 earthquake, the August 12, 2012 M_S6.3 earthquake, and the February 12, 2014 M_S7.3 earthquake respectively with the epidemic-type aftershock sequence (ETAS) model. We set a unified cutoff magnitude M_c=M_L3.0 and adopted the maximum likelihood method to estimate the parameters α, p and b of these sequences with different duration times. It is observed that the α, p and b value are significantly different for the three earthquake sequences. The α value of 2014 M_S7.3 earthquake sequence is close to the 2012 M_S6.3 earthquake sequence, and larger than that of the 2008 M_S7.3 earthquake sequence; a smaller p value of the 2014 M_S7.3 earthquake sequence indicates that it has a slow decay rate of aftershocks compared with the other two sequences; the b value of 2014 M_S7.3 earthquake sequence is larger than the 2008 M_S7.3 earthquake sequence, but smaller than the 2012 M_S6.3 earthquake sequence. Moreover, the parameters of 2008 M_S7.3 earthquake sequence change significantly within 20 days after the mainshock, while the α and p values of the 2014 M_S7.3 earthquake sequence keep stable in the first 3.5 days.