BACKGROUND: Childhood is a critical period for brain growth and cognitive development, most of the previous research examined the impact of family socioeconomic status (SES) on cognitive functioning primarily focused on middle-aged and older adults. We aimed to examine the association between family SES in childhood and offspring's cognitive performance in later life, and whether the relationship was mediated by parental healthy lifestyle. METHODS: A total of 5467 children aged 6-15 years were included in 2010 as baseline and 1789 offspring aged 14-23 years who had valid cognitive test scores were investigated in 2018. Multivariable linear regressions were utilized to estimate coefficients and 95 % CI for the association between family SES during childhood and children's cognitive performance in later life. The mediating effects of parental health lifestyle factors were calculated by the mediating model. RESULTS: Family SES during childhood was significantly associated with offspring's cognitive performance (p <
0.05). Parental partially mediated the association between family SES and cognitive performance (p <
0.05). Girls from upper medium household yearly income families had better cognitive performance (β = 2.64, 95%CI: 0.49-3.36). In the 14-17 years group, household yearly income was positively associated with cognitive performance (β = 1.60, 95%CI: 0.15-3.04). LIMITATION: The data was obtained through participants' retrospective self-reporting. CONCLUSION: Higher family SES during childhood may promote offspring's cognitive development in later life. The negative impact of low family SES could be mitigated through interventions and by encouraging parents to adopt healthier lifestyles.