Crop coefficient is an important parameter for estimating the change of water demand in crop growing season. Based on the meteorological and spring maize observations of 107 meteorological stations in the Northeast China from 1951 to 2018, the spring maize coefficients calculated by the model of crop coefficients were validated by using different crop coefficient correction formulas. The interannual variation trends and spatial distribution characteristics of crop coefficients during the whole period and each growth stage were analyzed by using spatial interpolation. The results showed that the single crop coefficient method considering the influence of wind speed and humidity had the best effect on the simulation of crop coefficient in the early stage of spring maize (R2=0.65). The coefficient of spring maize crops in the full growth period in the Northeast China was varied from 0.756 to 0.815. The spatial distribution of highvalue areas was mainly distributed in the western part of Northeast China, and the lowvalue areas were mainly distributed in the northern part of Heilongjiang Province and the southeastern part of Liaoning Province. Crop coefficients at different fertility stages were the largest in the middle of fertility, followed by the rapid growth period, and the early and late stages of childbearing were generally small. In the past 70 years, the interannual variation of crop coefficient of spring maize in the Northeast China showed a significant downward trend (R2=0.38), and the tendency rate of crop coefficient reached -0.004/(10a). In each reproductive period, the interannual changes of Kc showed a declining trend, Heilongjiang Province had the most obvious decline, followed by Jilin Province and eastern part of Inner Mongolia Autonomous region, changes of Liaoning Province were not obvious. The crop coefficient of most stations in Northeast China showed a decreasing trend, the decreasing trend and the significant decreasing trend accounted for 92.5% and 64.5% respectively. In different growth stages, the decline trend was the most obvious (46.7% in the rapid growth stage), and in the middle and late growth stage (41.1% and 34.6% respectively), the trend of change was not significant at the early stage of birth.