Grifola frondosa polypeptide-zinc chelate (GPs-Zn) is the chelation product of Grifola frondosa polypeptides (GPs) and zinc ions. GPs-Zn was subjected to structural characterization using scanning electron microscopy, X-ray powder diffraction, infrared spectroscopy, and ultraviolet spectroscopy. The effects of GPs-Zn on the offspring of zinc-deficient pregnant mice were explored by constructing an adult female ICR mouse model of zinc deficiency. Characterization results showed that GPs and zinc ions formed a novel substance through chelation; IR spectral comparison revealed that both amino and carboxyl groups on the peptide chain participated in the coordination reaction of zinc ions. The UV spectrum of GPs-Zn exhibited a red shift attributed to the binding of the carbonyl atoms of the peptides to zinc ions, indicating that GPs bound to zinc ions to form GPs-Zn. Animal experiments showed that GPs-Zn increased the thymus index of zinc-deficient offspring by 78.69% (female rats) and 87.55% (male rats), the spleen index by 40.28% (female rats) and 43.22% (male rats), the body weight by 89.98% (female rats) and 88.30% (male rats), the superoxide dismutase (SOD) activity in serum by 108.07% (female rats) and 26.16% (male rats), and the zinc concentration by 14.74% (female rats) and 29.33% (male rats), but decreased the serum alkaline phosphatase (AKP) activity by 52.28% (female rats) and 62.48% (male rats). GPs-Zn can improve the thymus index, spleen index, SOD activity, zinc concentration, and AKP activity of the offspring of zinc-deficient pregnant mice.