Abstract: OBJECTIVE To isolate and characterize some properties of the chromatographically pure low molecular weight polypeptides from the venom of Guangdong cobra (Naja naja atra). METHODS Isolation and purification were carried out by chromatography on Sephadex G-50 and UND Sphere S column after the pretreatment by chemical precipitation. The purity of this product was determined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and HPLC, and its molecular weight was observed by SDS-PAGE and mass spectrography. The cardiotoxicity of the polypeptides was investigated using the frog heart perfusion experiment. RESULTS After the chemical precipitation and Two-step column chromatography, the products, named ‘GI2’ and ‘GI3’, were single components. The molecular weight of GI2 is 14 300 Da observed by SDS-PAGE and GI3 is 6 725.8 Da determined by mass spectrography. The yields of the products were 9.5% and 10.1%, and only GI2 showed cardiotoxicity. CONCLUSION Two low molecular weight components could be obtained from the venom of Guangdong cobra after chemical precipitation and two-step column chromatographies, with high yield.