The study on the relationships between two copepod species Eurytemor affinis and Sinocalanus tenellus and Chinese mitten crab Eriocheir sinensis larvae in the ecological breeding ponds of E. sinensis larvae in Liaohe Delta district of Panjing City, Liaoning Province showed that E. affinis and S. tenellus had significant effects on the survival rate of first stage zoae (Z1). The higher the density of the two copepod species, the lower the survival rate of Z, was (P < 0.01). Third stage zoae (Z3) could prey on the copepods nauplii, and the feeding amount was increased with the increasing density of the nauplii (P < 0.01). Fifth stage zoae (Z5) and megalopae could easily prey on E. affinis, but not on S. tenellus. The megalopae yield in the ecological breeding ponds was negatively correlated with the quantity of the copepods during early breeding stage of E. sinensis larvae, and there was a significant difference among the megalopae yields when different quantity of copepods existed (P < 0.01). Some measures for controlling and utilizing the copepods in ecological breeding ponds of E. sinensis larvae were put forward.