Abstract: To investigate the immunomodulatory function of giant salamander peptide-selenium chelates, macrophage RAW 264.7 proliferation rate and cyclophosphamide-induced immunocompromised mouse model were used to evaluate the immunomodulatory activities of giant salamander peptide and its selenium chelate in vitro and in vivo, and the acute toxicity test was also performed. The results showed that the macrophage RAW 264.7 proliferation rates of giant salamander peptide and its selenium chelates displayed a tendency to increase and then decrease with the increase of their mass concentrations. During 4 weeks of gavage, different doses of giant salamander peptide 100 mg/(kg·bw) and 400 mg/(kg·bw) as well as giant salamander peptide-selenium chelates 10 μg/(kg·bw) and 30 μg/(kg·bw) restored the body weights and immune organ indexes of the mice (P<0.05), improved the histological structure of spleen, thymus, and liver, and increased the spleen lymphocyte proliferation level (P<0.05). Meanwhile, they enhanced the phagocytosis ability of abdominal macrophages, significantly increased the levels of interferon-γ, tumor necrosis factor, interleukin-6 and immunoglobulin G (P<0.05), and decreased the expression of Nod-like receptor3 (NLRP3) proteins in the mice spleens. The median lethal dose (LD₅₀) of giant salamander peptide-selenium chelates was 75.55 mg/kg, which could be ascribed to medium toxic. Compared with the giant salamander peptide, the giant salamander peptide-selenium chelates showed better immunomodulatory activity in vitro and in vivo.