[Aim]  To clarify the effects of sublethal concentrations of deltamethrin on the predatory insect Eocanthecona furcellata. [Methods]  The topical application method was used to determine the toxic response of E. furcellata to deltamethrin. Adults were treated with sublethal concentrations of deltamethrin (LC₁₀, LC₁₅, and LC₂₀), and the developmental duration, fecundity, survival rate, and the lifespan of female and male adults in the F₁ generation were measured. An age-stage life table was also constructed for each sex. [Results]  Exposure to sublethal concentrations of deltamethrin generally shortened the developmental duration of nymphs. Treatment with LC₁₀, LC₁₅, and LC₂₀ concentrations of deltamethrin significantly reduced female fecundity by 24.68%, 29.04%, and 37.53%, respectively, relative to the control group (P = 0.009). Treatment with the above concentrations of deltamethrin also significantly (P < 0.05) shortened the mean generation time (T), by 3.19%, 9.70%, and 9.40%, respectively, relative to the control group. However, deltamethrin did not cause any significant change to the intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R₀), of treatment groups relative to the control (P > 0.05). [Conclusion]  Sublethal concentrations of deltamethrin both shortened the survival time of the E. furcellata F₁ generation, and significantly inhibited female fecundity, thereby reducing population growth.