Provided is a new conotoxin peptide κ-CPTx-btl02. The conotoxin peptide κ-CPTx-btl02 has derivative polypeptide that has an amino acid sequence indicated by SEQ ID NO:1, or has derivative polypeptide that has an amino acid sequence indicated by SEQ ID NO:1 and that is formed after substitution, addition or deletion of one or more amino acids are performed and has original functions. Also provided is polynucleotide for coding the peptide, comprising a constructed body of the polynucleotide, an expression carrier and transformed cells. A peptide preparation method and uses in the treatment of diseases related to a calcium ion channel.