Objective: To explore perceived social support levels of vocational school students and associated factors, so as to provide a basis for the fine tuned construction of social support networks for vocational school students. Methods: Adopting a combination of multi stage cluster sampling and convenience sampling method, a sample of 11 767 vocational school students in Shanghai City and Jiangsu Province were selected to conduct two surveys (November 2021 and November 2022) by using a self administered electronic questionnaire regarding personal, family, school information and the Child and Adolescent Social Support Scale (CASSS). Correlates were analyzed by generalized linear estimating equations (GEE). Results: The total perceived social support scores in percentage at baseline and follow up survey were (66.13±20.46) and (67.65±21.18). The results of GEE showed that in terms of personal characteristics, girls had higher emotional support and evaluative support scores than boys ( B=0.60, 0.68, P < 0.05 ); extraversion, non-smoking, non-drinking, exercising ≥1 time per week, and better quality of sleep were positively correlated with the total score and the different types scores of precieved social support, and time spent on the Internet >2 h/d was negatively correlated with the total score and the different types scores of precieved social support ( B=1.03-4.49, -4.04--0.58, P < 0.05 ). In terms of family characteristics, parents not in marriage and living with (external) grandparents were negatively correlated with the total score and different types scores of percieved social support, while family characteristics such as satisfaction with family income (average, satisfactory, very satisfactory) and parents education level of junior high school and above were positively correlated with the total score and the different types scores of precieved social support ( B=-1.34--0.37, 0.57-2.37, P <0.05). In terms of school characteristics, without experience of bullying in school and the number of same sex or opposite sex friends >1 were positively correlated with the total score and different types scores of perceptual social support, and without serving as an officer of a student organization was negatively correlated with the total score and the different types scores of precieved social support ( B= 1.21- 5.04, -2.00--0.76, P <0.05). Conclusions The levels of overall and different types of precieved social support among vocational school students need to be improved. According to individual, family, and school related factors of precieved social support can help to target the improvement of students precieved social support level.