Objective: To explore the effects of the school based integrated horticulture curriculum intervention on 24 hour activity behaviors among third grade primary school students, so as to provide reference for promoting children s health. Methods: In September 2023, a convenience sampling method was used to select 90 third grade primary school students from a primary school in Changsha. Participants were randomly assigned to an intervention group ( n =45) and a control group ( n =45) using a random number table. From February to May 2024, the intervention group received a 12 week integrated curriculum intervention, consisting of two 60 minute sessions per week and covering horticultural practice, home-school collaborative tasks and nutrition knowledge education. The control group continued with routine labor education courses. The triaxial accelerometer and multi sensor sleep monitoring device were used to objectively measure light intensity physical activity (LPA), moderate to vigorous physical activity (MVPA), screen based sedentary behavior (SSB) and sleep (SLP), durations in both groups. Data were analyzed using generalized estimating equations (GEE) and Mann-Whitney U tests. Results: The time, group and interaction effects of MVPA time and SLP time before and after intervention in two groups of primary school students were not statistically significant (Wald χ 2=1.54, 2.97, 0.85 ; 0.75, 1.05, 0.48), and the group effect of LPA time (Wald χ 2=1.24) and the time and group effects (Wald χ 2=3.02, 1.18 ) were not statistically significant (all P >0.05). There were statistically significant time and interaction effects for LPA time, as well as interaction effect for SSB time in two groups of primary school students before and after intervention (Wald χ 2=4.78, 3.95, 12.60, all P <0.05). After intervention, LPA time of intervention group [152.23(59.15, 245.80)min] was higher than that of control group [120.70(29.90, 201.20)min], and SSB time of intervention group [55.50(30.00, 125.50)min] was lower than that of control group [220.00(60.00, 285.00)min], with statistically significant differences ( Z =-2.46, -4.48, both P <0.05). Conclusion The school horticulture curriculum effectively enhances daily LPA and reduces SSB among third grade primary school students.