To optimize the ultrasonic-assisted extraction process of polyphenols from the leaves of ginkgo biloba ( PLGB) ,the single factor trials and response surface methodology(RSM)were employed.A central composite rotatable design(CCRD)with four inde-pendent variables:methanol concentration;ultrasonic power;extraction temperature and extraction time were used to study the yield of PLGB.Except these ,the inhibitory rate on soil urease activity of PLGB was also studied.Results demonstrated that the optimal conditions for the PLGB extraction were found to be methanol concentration of 67%v/v,extraction temperature of 61 °C,and re-fluxed at 350W for 30 minute,in which 63.4 mg PLGB g-1 was obtained.Results also showed that the inhibitory rate on soil urease activity reach 50%when the concentration of PLGB was 46.11 mg· mL-1 .Thus the PLGB would be a good potential urease inhibitor to increase the utilization ratio of urea.% 利用响应面分析法对超声波辅助提取银杏叶多酚的工艺进行优化研究。在单因素试验的基础上，选取甲醇体积分数、超声波功率、超声温度、超声时间作为考察因素，应用Box-Behnken中心组合设计，以银杏叶多酚得率为响应值，进行响应面分析。另外对银杏叶多酚抑制脲酶活性进行了研究。结果表明，超声波辅助提取银杏叶多酚的最优提取条件为：甲醇体积分数67％、超声波功率350W、超声温度61℃、超声时间30min。在此工艺条件下，银杏叶多酚的得率为6.34％。当银杏叶多酚含量为46.11 mg· mL-1时，银杏叶多酚对土壤脲酶活性的抑制率可达50％。因此，银杏叶多酚是一种较好的土壤脲酶抑制剂，可以用于提高尿素的利用率。
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