This study explored whether academic motivation(i.e., intrinsic motivation, extrinsic motivation, and amotivation) and major satisfaction mediate the relationship between social support(i.e., parents, teachers, and peers) and school engagement by Chinese vocational high school students. Data were collected from 554 students (i.e., 313 male students and 241 female students) from vocational high schools located in Yueyang, Hunan Province in China. It was observed that there were significant positive correlations among social support, intrinsic and extrinsic motivation, major satisfaction, and school engagement. On the other hand, amotivation showed negative correlations with other variables. Male students showed higher teacher support and parental support than female students, while female students showed higher peer support than male students. In addition, female students showed higher school engagement than male students, especially higher behavioral and emotional engagement. It was also found that academic motivation and major satisfaction were mediated in the relationship between social support and school engagement. The results of this study is expected to be used as basic data for seeking ways to improve school engagement of Chinese vocational high school students.