In order to analyze the ecological mechanism and the effect of coal ash pollution on distribution of Brachionus calyciflorus species complex in three lakes (Lake Hui, Lake Tingtang and Lake Fengming), the effects of aerated tap-water (control), and 20%, 40%, 60%, 80% and 100% volume fractions of settled coal ash water diluted by aerated tap-water on population growth rates, ratios mictic females/amictic females, ovigerous females/non-ovigerous females, and resting egg productions of sibling species I have been collected from Lake Hui, Lake Tingtang and Lake Fengming and sibling species Ⅱ have been collected from Lake Tingtang. The results showed that regardless of the volume fraction of settled coal ash water, sibling species I collected from all the three lakes had higher population growth rates (0.52 0.85 d^-1) and resting egg productions (1.60 12.11 ind./(4 d·5 ml)) which made possible for population spread, population establishment and gene flow. Sibling species Ⅱ collected from Lake Tingtang had much lower ratio mictic females/amictic females and resting egg production, and in the aerated tap-water, both of them were zero, which might be the main reason for that sibling species Ⅱ living in Lake Tingtang and Lake Fengming could not spread into Lake Hui. The volume fraction of settled coal ash water significantly affects only the population growth rates of both two sibling species collected from Lake Tingtang. All the volume fractions of settled coal ash water made the population growth rate of sibling species I higher than that in the control, and 60%, 80% and 100% settled coal ash water made the population growth rate of sibling species Ⅱ higher than that in the control, which indicated that the decreased rotifer density in natural water bodies polluted by coal ash did not attribute to the direct toxicity of elevated metal, salt concentrations, and pH level.