The invention relates to caffeine electronic cigarette liquid, which mainly comprises 3-5%w/v of tobacco leaf extract, 5-10%w/v of pure water, 3-5%w/v of tobacco essence, 0.1-3%w/v of guarana extract with 5% in concentration, 0.2-1%w/v of stabilizer, 3-8%w/v of thickening agent and the balance of propylene glycol. The invention uses caffeine instead of nicotine; and the caffeine is an excitant for the central nervous system, and can increase the content of adenosine cyclophosphate (cAMP) in the cells. A small or medium amount of caffeine taken can excite the cerebral cortex, boost spirits of the people, enhance the attention, self-confidence, working efficiency and enthusiasm, shorten the time for selection and response and improve the recognition capability and instantaneously oral memory. In addition, the caffeine can promote synthesis and release of catecholamine, have positive effects to the cardiovascular system, promote gastric acid secretion, reduce the gallstone morbidity, and treat hemicrania and the like.