为探索露地蔬菜中残留农药降解较快的主要原因,以吡虫啉为供试农药,以不结球白菜(Brassica rapa L.Chinensis Group.,俗称小白菜)为代表作物,采用人工模拟降雨研究了不同降雨强度、降雨间隔、降雨次数及农药剂型对吡虫啉在蔬菜中残留量的影响。结果表明:吡虫啉在小白菜中的残留量随着降雨强度的增大而降低,随着降雨间隔时间的延长而升高,随着降雨次数的增多而降低,且连续降雨对吡虫啉的淋失作用大于间断降雨;降雨对小白菜上吡虫啉水分散粒剂的淋洗率高于对乳油的淋洗率。 In order to explore the main reasons for the rapid degradation of residual pesticides in open-field vegetables, taking imidacloprid as test pesticide and Brassica napus L.Chinensis Group as the representative crop, Effects of rainfall intensity, rainfall interval, number of rainfalls and pesticide formulations on residues of imidacloprid in vegetables. The results showed that the residues of imidacloprid in Chinese cabbage decreased with the increase of rainfall intensity, increased with the extension of rainfall interval, decreased with the increase of rainfall number, and leaching of imidacloprid by continuous rainfall More than the intermittent rainfall; rainfall leaching rate of cabbage imidacloprid water dispersible granules than leaching rate of EC.