Based on the balanced panel data of main summer maize producing areas in Henan province from 1993 to 2020, this study uses FGLS model to analyze the impact of precipitation at different growth stages on summer maize yield under climate change. The results show that the estimations measured by the whole summer maize’s growth period are significantly different from those measured by different growth stages. There are significant nonlinear and inverted U-shaped relationships between summer maize yield and precipitation at heading stage with optimal points. Drought reduces the summer maize yield at seeding, heading, and filling stage, but irrigation alleviates the adverse effects of insufficient and uneven precipitation on the summer maize yield. Besides, proper temperature rises at heading stage benefits the increase of summer maize yield, but high temperate significantly reduces the summer maize yield at elongation, heading and filling stage.