In previous studies on social stratification and mobility in China, education is considered as the core mediatory factor in social reproduction and mobility. This paper, however, investigates how childhood health affects social stratification. Using data from Urbanization and Labor Migrant National Survey (2012), this study examines the effects of nutrition, hygiene, and health before age 14 on adult socioeconomic status attainment, including education, the international socioeconomic indexes of first job and current job, and family income per head. The structural equation model results show that the nutrition intake (whether one experienced starvation and the frequency of fish and meat intake) and hygiene (indicated by the source of drinking water and the toilet type) have significant effect on adult socioeconomic status attainment. However, the effects change at different life course stages. Moreover, childhood health (indicated by adult height) has significant impact on adult socioeconomic status attainment, but no significant impact on the international socioeconomic indexes of first job and current job. We conclude that investment in childhood health is an important mechanism affecting social class reproduction and mobility. Therefore, health intervention for children from poor and disadvantaged families are necessary. It will benefit children’s education and encourage upward mobility.