This study extracted natural caffeine from green tea with distilled water as solvent. It was discovered the effect factor about the extraction yield of caffeine depended on the extraction time ,the ratio of tea and water quality,the quantity of lime,the extraction device,the sublimation device and other factors. The experiment re-sults showed:the extraction yield was 1.03%when the extraction time was 1.5 hours ,the ratio of tea and water quality was 1∶8 and the concentrated liquid lime dosage was 3.5 g. Compared with traditional Soxhlet extraction device,the constant pressure funnel device not only saved the cost and energy, but also had advantages of con-venient operation and saving time;Using water as the solvent was to avoid the pollution which accorded with the idea of green chemistry;In addition, the sublimation effect of electric heating sleeve was obviously better than alcohol lamp. This method can be used in all kinds of tea caffeine extraction.%以蒸馏水为溶剂从绿茶中提取天然咖啡因，探讨提取时间、茶水质量比、生石灰加入量、浸提装置、升华装置等因素对天然咖啡因提取率的影响。结果表明：当提取时间为1.5 h、茶水质量比为1∶8、所得浓缩液中生石灰加入量为3.5 g时，咖啡因的提取率为1.03%。恒压漏斗装置与传统的Soxhlet提取器相比，不但节约了成本及能源，而且具有操作简便和节省时间等优点；试验以水为溶剂避免了污染，符合绿色化学的思想；此外用调温电热套进行升华的效果明显优于酒精灯，这种方法可在各类茶叶咖啡因的提取中推广使用。
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