Taking Xianyu 335 as experiment material, effects of plant growth regulator on the stem agronomic charac-ters and yield of maize were studied. The results showed that plant growth regulator reduced maize ear height. Withthe delay of regulator application stage, the plant height gradually decreased, ear height gradually increased, influ-enced basal internode moved upward. The internodes below ear were shorter, thicker, stronger, the internodes aboveear elongated obviously, the stem dry weight above ear gradually decreased, the center of plant gravity decreased.Plant growth regulator raised maize yield, and within the testing range,‘Yuduoshi’spraying at 8 leaf expansion wasbetter.