This paper presents the first comprehensive systematic review and meta-analysis of early childhood development (ECD) in rural China, synthesizing evidence from 45 studies involving more than 39,000 children and caregivers across 17 provinces. It quantifies the prevalence of cognitive, language, and social-emotional developmental delays, examines the role of caregiving practices and caregiver mental health, and evaluates the effectiveness of parenting interventions through randomized controlled trials. The findings reveal that developmental delays remain alarmingly common, while nearly one in four caregivers experience depressive symptoms, with grandmothers facing particularly high rates. At the same time, parenting programs consistently improve children's developmental outcomes and caregiver engagement, with home-based interventions producing significantly larger gains than center-based models. By identifying both the scale of the challenge and the program features that drive impact, this study provides one of the most comprehensive evidence bases to date for designing scalable, evidence-based parenting policies that can reduce developmental inequality and strengthen human capital in rural China.