With unprecedented migration taking place in China, millions of children are profoundly affected. Using a sample of 916 children (aged 5–18) of migrants and the life course perspective, this article examines the impact of parental migration on children's health. Results show that migration has a complex impact on children's health. Although migrating to cities itself does not benefit children, poor housing conditions in cities have a negative impact on their health. The timing of parental migration is important, as preschoolers migrating with parents and teenagers left behind by parents have significantly worse health than others. Migration also has a gendered effect, as teenage boys benefit from migrating to cities but suffer from being left behind when compared to teenage girls.