Research Findings: This study investigated children's feelings about school and their adaptation to primary school after leaving kindergarten. Altogether, 28,334 Chinese children (ages 6-8 years) were sampled and surveyed online. The descriptive statistic, latent class analysis (LCA) approach, and logistic regression analysis indicated that: (1) children generally had positive feelings toward school, especially about teacher-student relationships. However, the self-perception of academic abilities was less positive; (2) children's social adaptation had the highest scores, followed by life and physical adaptation, and then academic adaptation; (3) there were significant differences between children from only child and non-only child families both in school feelings and adaptation; (4) three latent classes of children's school adaptation emerged: the Well-Adapted Children were girls, only children in eastern China; the Moderately-Adapted Children were boys, non-only children in central China; the Poorly-Adapted Children were boys, non-only children in western China; and (5) children's school feelings significantly predicted their class membership for adaptation. Practice or Policy: These findings suggest that we need to focus more on children's feelings and academic school adjustment issues. Targeted support is needed for children at risk of school adaptation to help them transition smoothly to primary school.