Objective: To explore the characteristics of the patterns and differences in the time of 24 h activity behavior components among vocational college students with different body mass index (BMI) during semester and vacation, so as to provide the reference for optimizing the scientific development of healthy lifestyle in adolescents. Methods: From November to December 2022, a total of 162 freshman students from a vocational college in Wuxi were selected by random sampling. Based on gender and BMI, the subjects were divided into six groups:underweight, normal weight, and overweight and obese. In January, April, July and October 2023, a MIO smart heart rate wristband, weekly questionnaire and Bouchard physical activity diary were used to track the time of 24 h activity behavior components [physical activity (PA), sedentary activity (SB), moderate to vigorous physical activity(MVPA) and sleep behavior (SLP)] over one week. Repeated measurement analysis of variance was used to compare the inter group differences in these activity behavior components between male and female students. Results: The analysis of variance of repeated measurements showed that there were statistically significant main effects for group (gender) on PA, MVPA, SB, and sleep time ( F boys =241.62, 253.69, 210.66, 20.09; F girls =316.36, 286.41, 277.37, 7.68), as well as significant main effects for time ( F boys =342.72, 234.54, 77.77, 42.80; F girls =569.74, 155.14, 95.13, 52.67) ( P <0.01). Additionally, there was a statistically significant interaction effect between group and time ( F boys =16.63, 11.25, 8.91, 4.01; F girls =69.49, 10.69, 18.22, 3.89) ( P < 0.01 ). After inspection, the comparison of different BMI at each month showed that PA, MVPA time of male and female students in the normal weight group was longer than that of overweight and obesity group, and SB time in overweight and obesity group were longer than that of normal group, with statistical significances ( P <0.05). Except for October in boys and April in girls, where sleep time was longer in the normal weight group, the overweight and obesity group had longer sleep time in other months than the normal weight group, and statistically significant differences were observed only in January and July ( P <0.05). Comparison across different month within different BMI groups showed that the time of PA, MVPA initially increased, then decreased, and increased again over the year ( F boys =39.56-386.68, F girls =38.97-637.54), while SB and SLP time initially decreased, then increased and decreased again ( F boys =6.79-69.25, F girls =6.70-162.86), and the difference between semester (April and October) and holiday (January and July) were statistically significances ( P <0.01). Conclusions The time of 24 h activity behavior components of vocational college students is obviously different among different BMI groups and between semester and vacation. Tailored intervention measures should be formulated for both semesters and vacations based on the characteristics of vocational college students for promoting students to develop a good lifestyle.