Abstract: This paper difines the concept of the subsequence of earthquakes. The subsequences of the Xingtai earthquake swarm are analysed in several respects. Among the subsequence changes there are notably the changes with time. That is. the frequency of foreshocks and aftershocks tend to become less and the magnitudes smaller; the subsequence type transits from the swarm type to the isolated type; the decrease in epicentral intensities gradually becomes more conspicuous; the focal mechanisms tend to be consistent. In a sense, the changes mentioned above reflect the attenuation of the Xingtai earthquake sequence.