Abstract:Hypoglycemic polypeptide-K of bitter gourd seeds was to increase sensitivity of tissue to insulin and improve insulinresistance，which was remarkable hypoglycemic effect.In order to improve the extraction rate of polypeptide-K from bitter gourd seeds，breed varieties with high content of polypeptide K.In this study，five varieties of bitter gourd seeds were used materials，the single factor test optimization combined with alkali extraction-acid precipitation was used to extract the polypeptide-K.The results showed that alkali extractionacid precipitation method was used to extract the polypeptide-K.The optimum technological conditions were liquid ratio 1 ∶20（g/mL），alkaline solution pH 9.5，temperature 50 ℃，extraction time 60 min，acid precipitation pH 3.0.The extraction ratio of polypeptide K in bitter gourd seeds varieties was significantly different.The high content of polypeptide-K were Guinongke 9 and Green fruit bitter gourd seeds，and Guinongke 9 was the highest，which was 2.06 mg/g.After optimization of alkali extraction and acid precipitation process，the extraction of polypeptide K was 0.18 mg/g.