Abstract: The invention belongs to the field of biochemistry and molecular biology. The present invention provides a mutant of ?-conotoxin peptide TxID, a pharmaceutical composition and use thereof. The TxID mutant is capable of specifically blocking acetylcholine receptors (nAChRs), in particular, ?3?4, or ?6/?3?4 subtype, and has application prospects in the manufacture of a medicament for smoking cessation and detoxification and analgesia, a medicament for treating psychiatric diseases and cancers, regulating appetite, and a tool medicine for neuroscience.