Objective: To study the cause of rapid thrombocytopenia and organ hemorrhage in congenital heart disease (CHD) patients after interventional occlusion. Methods: A total of 665 CHD patients received interventional occlusion in our hospital from 2011-01 to 2015-12 were enrolled. The patients were divided into 3 groups according to the defects: Atrial septal defect (ASD) group,n=100, Ventricular septal defect (VSD) group,n=100 and Patent ductus arteriosus (PDA) group,n=465. Pre- and post-interventional occlusion platelet levels, the relationship between PDA occluder diameter and platelet counts were compared. Pressure difference between both sides of occluder was randomly measured in a part of patients including 50 in ASD group, 50 in VSD group and 102 in PDA group. Based on occluder diameter, the 102 PDA patients were further divided into 2 subgroups: Giant PDA,n=42 and Medium-small PDA,n=60; pressure differences between both sides of occluder were compared between 2 subgroups. Results: No severe thrombocytopenia and organ hemorrhage occurred in ASD group or VSD group. PDA group had 36/465 (7.74%) patients with severe thrombocytopenia, 18 (3.87%) with organ hemorrhage and all of them occurred in giant PDA subgroup; the diameter of PDA occluder was negatively related to post-operative to platelet counts (r=-0.659,P=0.001). For pressure difference on both sides of occluder, compared with prior operation, PDA group showed increased systolic and diastolic pressure differences and increased mean pressure difference at immediately post operation, allP< 0.05; systolic pressure difference in VSD group was (56.57±15.33) mmHg, in Medium-small PDA subgroup was (58.33±26.65) mmHg and in Giant PDA subgroup was (94.66±27.62) mmHg which was much higher than those in VSD group and Medium-small PDA subgroup, allP<0.01. Conclusion: Rapid thrombocytopenia and organ hemorrhage in CHD after interventional occlusion only happened in giant PDA patients. High pressure difference formed high-speed ifltration blood lfow which may cause scouring damage on platelets and it was the main reason for thrombocytopenia occurrence.