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Zinc is an essential micronutrient crucial in various biological processes of an organism. However, the effects of zinc vary depending on its chemical form. Therefore, the aim of this study was to conduct a comparative analysis of the life history performances and hemolymph metabolism of <i>Spodoptera litura</i> exposed to different concentrations of dietary zinc chloride (ZnCl₂) and zinc sulfate (ZnSO₄), utilizing two-sex life tables and untargeted metabolomics. The preadult survival rate of <i>S. litura</i> significantly decreased, while the preadult developmental period of <i>S. litura</i> was prolonged as the dietary ZnCl₂ concentration increased. However, the fecundity of <i>S. litura</i> at 50 mg/kg dietary ZnCl₂ was significantly increased. The intrinsic rate of increase (<i>r</i>) and the finite rate of increase (λ) in <i>S. litura</i> in the control group (CK, no exogenous ZnCl₂ or ZnSO₄ added) and with 50 mg/kg dietary ZnCl₂ were significantly higher than those at 100 mg/kg, 200 mg/kg, and 300 mg/kg. Dietary ZnSO₄ exerts a devastating effect on the survival of <i>S. litura</i>. Even at the lowest concentration of 50 mg/kg dietary ZnSO₄, only 1% of <i>S. litura</i> could complete the entire life cycle. Furthermore, as the dietary ZnSO₄ concentration increased, the developmental stage achievable by the <i>S. litura</i> larvae declined. High-throughput untargeted metabolomics demonstrated that both 100 mg/kg dietary ZnCl₂ and ZnSO₄ decreased the hemolymph vitamins levels and increased the vitamin C content, thereby helping <i>S. litura</i> larvae to counteract the stress induced by ZnCl₂ and ZnSO₄. Simultaneously, dietary ZnCl₂ obstructed the chitin synthesis pathway in the hemolymph of <i>S. litura</i>, thus extending the developmental period of <i>S. litura</i> larvae. These results indicate that low concentrations of Zn²⁺ positively impact populations of <i>S. litura</i>, but the effectiveness and toxicity of Zn depend on its chemical form and concentration.