Abstract: To determine the optimal spraying period of uniconazole (S-3307) for enhancing the seed yield of Pisum sativum, this study conducted foliar applications at the initial flowering stage (T₁), full flowering stage (T₂), and late flowering stage (T₃). At the podding stage, parameters including stem diameter, plant height, branch number, weight per plant and SPAD value were assessed. Subsequently, at maturity, conventional methods were employed to examine the beginning pod height, number of stem nodes, number of first pod nodes, stem length, total pod stem nodes length, number of pod nodes, number of pods, seeds and pod set rates on the main stems. The results showed that foliar spraying of S-3307 in all three periods could effectively inhibit plant height and increase stem diameter, SPAD value, biomass per plant, but had little effect on branch number. Among them, T₁ treatment had a more significant effect on inhibiting plant height and promoting stem diameter, and T₃ treatment had a more significant effect on promoting fresh and dry weight per plant. The foliar spraying of S-3307 in three periods could reduce the main stem length, beginning pod height and number of first pod nodes, and promote the increase of the number of pod nodes, total pod stem nodes length, number of pods, seeds, pod set rates and seed set rates, and the effect of T₃ treatment was more significant. T₂ and T₃ significantly reduced the contents of GA₃, IAA and ABA, as well as the GA₃/ABA and IAA/ABA ratios in pods, while significantly increasing the CTK content and the CTK/ABA ratio. Among these, T₃ showed the greatest changes, whereas T₁ exhibited no obvious changes. Compared with spraying water control, T₃ treatment could significantly increase the seed yield by 19.93%, while T₁ and T₂ treatment could increase the seed yield by 7.33% and 3.87%, respectively, with no significant difference. Therefore, the late flowering stage is the critical period for spraying S-3307 to inhibit ineffective growth and achieve increased seed yield in Pisum sativum. By elevating CTK content while reducing GA₃, IAA and ABA levels and their corresponding hormone ratios in pods, this approach helps maintain hormonal equilibrium, which in turn decreases pod shedding, facilitates pod development and grain formation, and ultimately enhances the final seed yield.