The seasonal dynamics of the acanthocephalan Micracanthornhyachina motomurai in the three small cyprinids, Opsariichthys uncirostris, Zacco platypus and Hemiculter bleekeri bleekeri in the Danjiangkou reservoir was investigated from February 2004 to February 2005. The prevalence and abundance of the acanthocephalan exhibited very similar and significantly seasonal change patterns in O. uncirostris and H. bleekeri bleekeri. The infection levels were higher in autumn and winter, but lower in spring and summer. However, the infection levels in Z. platypus kept stable all the year round. There were significant differences among the overall abundance of the acanthocephalan in the three host populations. Nevertheless, the frequency distribution of the parasite in the three kinds of fish was over-dispersed in most seasons and in total as measured by the variance to mean ratio. The variance to mean ratio was not found related to the infection levels.