Abstract: Based on the phenological data of spring maize and meteorological observation data at Jinzhou agrometeorological observation station from 1980 to 1984 and 2004 to 2020, the changing trends of spring maize growth period length and hydrothermal factors at the same time were studied using the methods of trend coefficient, tendency rate, correlation analysis, and path analysis.In addition, the relationship between spring maize growth period length and hydrothermal conditions was discussed.The results show that each of the growth period lengths of spring maize in Jinzhou has different trends from 1980 to 1984 and 2004 to 2020.Except for tasseling period, maturity period, and reproductive growth period, the length of other growth periods shows a shortening trend.Particularly, the length of the vegetative growth period is significantly shortened, while the length of the reproductive growth period is significantly prolonged, The whole growth period shows a weak extension trend, and the change is not obvious.The changing trend of hydrothermal conditions in each growth period of spring maize is different.The variation of heat conditions is large, while the variation of water conditions is relatively small.The active accumulated temperature ≥ 10 ℃ (DT10) and Growth Degree Day (GDD) in most growth periods show an increasing trend, and there is a very significant increase in tasseling period, maturity period, reproductive growth period, and whole growth period.It can be seen that heat conditions have a great impact on the growth and development of spring maize.Correlation analysis and path analysis show that both DT10 and GDD have a great effect on the growth period length of spring maize, while water conditions have less effect.The length of seedling period, maturity period, and whole growth period are significantly correlated with water conditions.The water and heat factors restrict and influence each other, and jointly affect the whole growth period of spring maize.