Objective: To explore the impact of public health interventions (strict non-pharmaceutical measures and subsequent relaxation) on the epidemiological trends and clinical characteristics of childhood Chlamydia pneumoniae (CP) pneumonia in Beijing, and provide evidence for precise prevention and treatment. Methods: A retrospective cohort study enrolled 331 hospitalized children with laboratoryconfirmed CP pneumonia (January 2017–September 2025) from the Capital Center for Children's Health, stratified into three groups by intervention intensity . Demographic and clinical data were collected and analyzed. Results: Among the 331 patients (male:female=1.75:1), the post-intervention group (Jan–Sep 2025) showed a significant surge, accounting for 7 .91% of community-acquired pneumonia (CAP) cases. The primary affected age shifted from 0–3 years (pre-intervention: 60.4%; duringintervention: 75.6%) to 6–18 years (post-intervention: 90.1%; H=172.24, P