Abstract: The invention provides a peptide capable of blocking voltage-gated K+ channels and inhibiting IL-2 production, which is represented by an amino acid sequence of: Ala-Ser-Cys-Arg-Thr-Pro-Lys-Asp-Cys-Ala-Asp-Pro-Cys-Arg-Lys-Glu-Thr-Gly-Cys-Pro-Tyr-Gly-Lys-Cys-Met-Asn-Arg-Lys-Cys-Lys-Cys-Asn-Arg-Cys; in which the C-terminal is amidated and four disulfide bridges are present in the molecule, and their related peptides isolated from the venom gland of a scorpion Heterometrus spinnifer. The peptides provided by the present invention are neuropeptides which can block voltage-gated K+ channels and inhibit IL-2 production at an extremely low concentration and, therefore, are expected to contribute to application of scorpion toxins to medicines and so on.