Abstract: A neurotoxin named Hainantoxin-Ⅵ (HNTX-Ⅵ) was purified from the venom of the hinese bird spider Selenocosmia hainana by ion exchange chromatography and r everse phase high performance liquid chromatography.The molecular weight of HNTX-Ⅵ is 3.99 849 kDa identified by MALDI-TOF mass spectrometry,which is in good agreement with the complete amino acid sequence of NH2-ECKYLWGTCEKDEH CCEHLGCNKKHGWCGWDGTF-COOHdetermined by automatic Edman degradation.The neurotoxin can paralyze rat after intracerebroventricular injection and block the neu romuscular transmission of the isolated rat phrenic nerve-diaphragm preparation .The 34-residue peptide,which contained 6 Cys and formed three disulfide bond s,showed high homology with two kinds of K+ channel inhibitor,the HaTx from the venom of the Grammostola spatulata and the SGTx1 from the tarantula Scodra griseipes.