Abstract: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 results 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 convenient 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.