Abstract: In this study, the effects of NaCl, PEG（6000） and low temperature stresses on the levels of iATP（intracellular ATP） and eATP（extracellular ATP） of tobacco suspension cells BY-2（Nicotiana tabacum ’Bright Yellow-2’） were studied respectively. The results showed that the tobacco suspension cells treated with 50-200 mmol·L^-1 NaCl significantly increased membrane permeability（P＜0.05）, the levels of iATP and eATP decreased significantly at 100 and 200 mmol·L^-1 NaCl stresses（P＜0.05）. With the increase of PEG mass concentration(50, 100 and 200 g·L^-1), the membrane permeability and eATP level increased. Under 200 g·L^-1PEG stress, eATP level increased significantly to 3.4-fold of the control（P＜0.05）, iATP level decreased significantly to 0.5-fold of the control（P＜0.05）. After the treatment with low temperature at 0-10 ℃, the membrane permeability and iATP level increased to different extents. iATP level increased to 1.9-fold of the control at 0 ℃, while eATP level decreased significantly to 0.8-fold the control at 10 ℃（P＜0.05）. The above results indicate that iATP is the source of eATP in plant cells, iATP level is not the only factor that affects eATP level under abiotic stresses. The way in which plant cells transport ATP and other factors may affect eATP level under abiotic stresses.