This paper introduces a method calculating the relative fractal factor and has calculated the relative fractal factors(D₂)of after-shock sequences of the Leipo earthquake(Ms=5.4), two Kangding earthquakes(Ms=5.2, 5.8)and the Dayi earthquake(Ms=6(1)/(4)), using this method. The D₂ factors, for above mentioned four earthquakes, are 2.26982, 1.93915, 2.28738 and 1.5367 respectively. Relative coefficient and related departure of every D₂ are calculated and given. The D₂ factor of aftershock sequence in which the strong aftershock occurred is larger than that of aftershock sequence in which the strong aftershock did not occur.