Objective: To analyze the independent and interaction effects of daytime outdoor light exposure and moderate to vigorous physical activity (MVPA) duration on sleep quality of primary school students, so as to provide scientific evidence for interventions on children s sleep health. Methods: From April to June 2024, a total of 444 students from grades 3 and 4 in 2 primary schools in Jiading District, Shanghai were selected using stratified random cluster sampling method for continuous 7 day monitoring. Wearable devices "Clouclip" were used to monitor daytime outdoor activity time (represented by time with light intensity ≥ 1 000 lx ), and accelerometers were used to monitor MVPA time and sleep quality related indicators. Multiple linear regression was used to analyze the associations of daytime outdoor activity and MVPA with sleep quality. Results: Both daytime outdoor light exposure and MVPA duration(longer actual sleep duration per night,longer time in bed,fewer awakening and shorter post sleep awakening shic) were independently associated with multiple sleep indicators( β =0.52, 0.46, -0.83, -2.19, all P <0.05), with no significant interaction between the associations ( P >0.05). After controlling for MVPA, more daytime outdoor light exposure was significantly and independently associated with longer actual sleep time ( β =0.50, 95% CI =0.21-0.79, P <0.05). After controlling for light exposure, longer MVPA duration was independently associated with shorter post-sleep awakening duration ( β=-4.15, 95% CI = -6.33 to -1.96, P <0.05). Conclusion Increased daytime outdoor activity and MVPA are both associated with better sleep quality in primary school students.