Imidacloprid is a widely used insecticide for controlling piercing-sucking pests. However, its impact on nontarget insects must not be ignored. In this study, we assessed the effects of sublethal dose of imidacloprid on Sclerodermus alternatusi (Hymenoptera: Bethylidae), which is an important predator of many pests. The data indicate that imidacloprid at LD₁₀ (0.1468 ng active ingredient per insect) and LD₃₀ (0.2376 ng active ingredient per insect) significantly reduced the longevity and fecundity of the F₀ generation of S. alternatusi. However, the adult female longevity of the F₁ generation of the LD₁₀ dose group showed a significant increase, and the LD₃₀ dose group showed a nonsignificant increase. The study found that as the imidacloprid dose increased, the intrinsic rate of increase (r) decreased, while the mean generation time (T) increased. The imidacloprid groups also showed a decrease in age-stage specific survival rate (S_xj) and age-specific survival rate (l_x). However, the female age-specific survival rate (f_x4) showed an increasing and then decreasing trend for all treatments. The study found that imidacloprid had an impact on the longevity of S. alternatusi in the F₀ generation and extended the mean generation time (T) in the F₁ generation. However, it had negative effects on population growth parameters. These findings can be used as a basis for developing integrated pest management strategies.