Based on the daily meteorological dataset during 1965 to 2006 from 10 meteorological stations in Linghe basin of Liaoning province, the reference evapotranspiration (ET_0) was calculated using P - M equation recommended by FAO.And with the analysis of variation trend relating to meteorological elements and ET_0 during growing season (from April to September), the contribution to ET_0 change made by meteorological alteration was also discussed with a method based on sensitivity coefficient.The results showed that the average value of ET_0 during growing season in Linghe basin was 706.73mm and it was significantly reducing at a speed of 21.46mm · 10y~(-1) in the past 42 years(P<0.01).During the whole season, the ET_0 in May accounted for the most while that in Sep.came the least.The high value of ET_0 concentrated in Chaoyang and Yangshan and the low value was in Yixian.The average solar radiation of whole growing season in the study area was declining at a speed of 0.293MJ · m~(-2)·d~(-1)·10y~(-1).Except in Fuxin station, the wind speed was significantly decreasing (P<0.01).Under the background of global warming, the average temperature of Linghe basin in growing season during the past 42 years was increasing at a speed of 0.289℃ ·10y~(-1)and the trend was obvious in April and September(P<0.05) while that was relative stable in July.The change of relative humidity during growing season in the study area was not serious.The sensitivity analysis results showed that the sensitivity order of average ET_0 in Linghe basin to different meteorological elements in growing season was:solar radiation > relative humidity > wind speed > temperature.But as to contribution value, the significantly changed wind speed was the most important factor to ET_0 variation, followed by solar radiation, and the temperature did the least to ET_0 variation.Meanwhile, the contribution of solar radiation and wind speed change to ET_0 variation in western basin was greater, and smaller in the east, while that of temperature showed a progressive decrease tendency from the middle to both sides on the whole.The contribution of relative humidity change to ET_0 alteration was scattered on spatial distribution.