Abstract: Based on the daily meteorological data of 9 flue-cured tobacco growing counties in western Henan Province from 1970 to 2019, the water requirement was calculated by Penman-Monteith formula.In addition, the effective precipitation of fluecured tobacco fields in the study area was calculated by effective precipitation coefficient method and then the irrigation water demand was obtained.The temporal and spatial variation characteristics of water requirement and irrigation water demand as well as meteorological influencing factors were analyzed by the use of climate trend rate method, trend coefficient method, Morlet wavelet analysis and partial correlation analysis.The results showed that from 1970 to 2019, the annual average precipitation and effective precipitation during the field period of flue-cured tobacco in western Henan Province were 425.1 mm and 309.3 mm, respectively, and both of the two maintained an upward trend at a rate of 1.15 mm/10 a and1.752 mm/10 a, respectively.The annual average water requirement and irrigation water demand were 473.7 mm and 167.5 mm and showed a very significant downward trend at a rate of -8.436 mm/10 a and -10.188 mm/10 a respectively.The wavelet analysis showed that the water requirement for flue-cured tobacco and irrigation water demand had a main change period of 25 years and 17 years, and they increased progressively from the south to the north from the perspective of spatial distribution, with the high value areas mainly distributed in Sanmenxia and Mianchi and the low value areas in Luanchuan, Lushi and Songxian.Partial correlation analysis of climate factor change showed that the decrease of sunshine hours was the main meteorological factor leading to the decrease of flue-cured tobacco water requirement and irrigation water demand in the study area.