BACKGROUND: Childhood obesity is a critical public health concern in China. This study identified the key determinants of childhood obesity in China and provided recommendations for future intervention strategies. METHODS: We conducted a comprehensive systematic review and meta-analysis to identify multiple-level determinants of childhood obesity in China and calculated the population-attributable risk percentage (PAR%) for each modifiable determinant. We also conducted expert consultations using the Socio-ecological Model to gain insights into the causes of obesity. Additionally, we reviewed current Chinese policies on childhood obesity intervention and compared them with the priorities identified in the meta-analysis and expert consultation to pinpoint policy gaps. FINDINGS: Our meta-analysis, incorporating 419 studies, identified 33 risk factors for childhood obesity. At the individual-level, we identified 11 key contributors including early-life risk factors such as maternal pre-pregnancy overweight/obesity (PAR%: 16.7%), breastfeeding duration of less than six months (14.1%), cesarean section delivery (11.1%), excessive gestational weight gain (10.5%), high birth weight (4.2%), and gestational diabetes mellitus (3.6%), and 13 behavioral factors during childhood such as sugar sweetened beverage consumption (16.4%), insufficient sleep (15.0%), rapid eating speed (14.7%), less than 2 h of physical activity per day (6.3%), and over 2 h of daily screen time (5.6%). We also identified six prominent family-level factors such as maternal overweight/obesity (24.3%) and paternal overweight/obesity (23.5%). Expert consultation highlighted genetic factors, and prioritized actionable risk factors, particularly dietary, expanding on the meta-analysis findings. Finally, policy review revealed that existing Chinese policies inadequately addressed these determinants, especially at the macro and structural levels. INTERPRETATION: This study highlights the importance of targeting high-risk populations and addressing detrimental behavioral factors, especially on early-life influences. However, real-world impacts require a comprehensive approach that goes beyond individual factors. More future effective intervention efforts are needed. FUNDING: This study was funded by the National Natural Science Foundation of China (NSFC 82073567; NSFC 82273641) and the National Science and Technology Innovation 2030, Noncommunicable Chronic Diseases-National Science and Technology Major Project (Grant No. 2023ZD0508500, 2023ZD0508504).