The studies on exisistence of pre- nicotine and signal substances at different organs and leaf positions of tobacco plant were reviewed, and the rule of nicotine synthesis and distribution were revealed. Nicotine synthesis influencing factors such as mineral elements of N, P, K, as well as other agronomic treatments including variety, topping, plant population, film- mulching, irrigation, maturity, external regulators, root slicing and rootcutting were discussed. The other influencing factors of soil, climate and elevation towards the nicotine concentration in tobacco leaves were also discussed.