Based on the daily meteorological data of 124 agricultural meteorological sites during 1977-2010 in Yunnan Province,using recommended Penman-Monteith formula by FAO,water requirement and irrigation requirement index in the growth period of flue-cured tobacco were calculated to analyze their spatial and temporal characteristics and change patterns. The results showed that water requirements of flue-cured tobacco in root extending,vigorous,mature periods and field growth period during 1977-2010 were 76.73-174.73,247.50-386.64,180.28-258.14 and 528.18- 764.08 mm,respectively,and the water requirement of vigorous period was the highest. The average irrigation demand index of each period was -0.02,0.38,0.17 and 0.26,respectively. Effective precipitation could meet the demand of flue-cured tobacco in root extending period. Water requirement of flue-cured tobacco in Yunnan Province decreased annually,and the rates of water requirement under the climate change trend in the four periods abovementioned were - 12. 42, -21.46,-7.17 and -47.15 mm·(10 a) ~(-1),respectively. The smallest irrigation demand index was observed in Dehong, and the largest in Diqing. The irrigation demand indexes of Dehong, Xishuangbanna and Puer regions were negative in flue-cured tobacco field growth period. The reference crop evapotranspiration,water requirement and effective precipitation decreased,but the irrigation requirement and irrigation requirement index increased with the increase of latitude. The effective precipitation decreased,but the irrigation requirement and irrigation requirement index increased with the increase of altitude.