Objective To evaluate the surgical treatment for congenital heart disease plus pulmonary artery hypertension (CHD-PAH) in children weighing less than 5 kg. Methods The clinical data of 29 CHD-PAH children with body weight ≤ 5 kg who were treated surgically between Aug. 2016 and Aug. 2018 were collected and retrospectively analyzed. Surgical complications and death causes were analyzed. Pulmonary artery pressure (PAP), the ratio of main pulmonary artery to ascending aorta diameter (MPA/AAO), the ratio of ventricular pre-ejection period to acceleration time (PEP/AT), arterial oxygen partial pressure (PaO₂), pulse oxygen saturation (SpO₂), the ratio of height to normal children, the ratio of weight to normal children, and functional classification of pulmonary arterial hypertension were evaluated in 26 survival children before surgery, before discharge and at 6 months after surgery. Results The procedures were finished successfully in all the 29 children. Postoperative complications were as follows:low cardiac output syndrome (LCOS, 2 cases), pulmonary hypertension crisis (1 case), residual shunt or recanalization (2 cases), arrhythmia (1 case), hepatic insufficiency (1 case), and delayed wound healing (2 cases). Three children (10.3%) died; of them 2 died of LCOS and one died of pulmonary hypertensive crisis. The above-mentioned indexes were significantly improved before discharge and at 6 months after surgery (P<0.05). The growth and development of 24 children reached the normal level 6 months after surgery. Conclusion Surgical treatment is safe and effective for CHD-PAH children with body weight ≤ 5 kg, which can restore normal growth and development of the children.