Objective To explore the strategy of pacemaker treatment in children weighing less than 8 kg. Methods The clinical data of 24 patients weighing less than 8 kg who underwent permanent pacer implantation in Shanghai Children's Medical Center from 2009 to 2019 were retrospectively analyzed. Results The median age of the 24 children ( 16 boys and 8 girls) was 6 . 5 months ( 1 - 22 months), the median weight was 6 . 4 kg ( 2 . 4 - 7 . 9 kg), and the median postoperative follow-up time was 20 . 5 months ( 1 - 120 months). Endocardial pacing was performed in 15 cases and epicardial pacing was performed in 9 cases. After endocardial pacing, capsular infection occurred in 3 of the 15 children and manifestations were local capsular hematoma, exudation, and surgical incision dehiscence respectively. All three children received intravenous anti-infective therapy. Two cases with exudation and surgical incision dehiscence underwent pocket debridement and re-embedded generator; the other one refused debridement. After endocardial pacing, 3 cases underwent second operation due to abnormal pacemaker function. In one case, the lead was replaced 3 months after operation due to tricuspid regurgitation. The lead and generator were replaced 6 years after operation in 1 case due to poor pacemaker perception. One patient underwent pacemaker implantation due to power depletion 9 years after surgery and the pacing mode was replaced considering that double-chamber pacing might be more in line with physiological characteristics. In 9 children who had epicardial pacing, two underwent second operation due to abnormal function of lead or pacemaker because of premature power depletion and they were replaced with endocardial pacemaker 1 . 5 and 2 years after the operation respectively. Conclusion Permanent pacemaker implantation via endocardium and epicardium for children under 8 kg is feasible, and is safe and effective under strict control indications. However, it needs to watch for capsular infection and tricuspid regurgitation during the operation and follow-up.