Objective To investigate pulmonary circulation effects of protamine different infusion ways on the acyanotic congeni -tal heart disease(CHD) patients with pulmonary arterial hypertension(PAH) after extracorporeal circulation surgery .Methods Se-lect 80 cases of the CHD patients prepared for extracorporeal circulation surgery ,according to the different routes of administration and with or without PAH ,80 patients are divided into 4 groups (n= 20) :A1(non-PAH ,aortic root administration) ,A2(non-PAH , central venous administration) ,B1(PAH ,aortic root administration ) ,B2 (PAH ,central venous administration) .pulmonary artery pressure(PAP) ,pulmonary venous pressure (PVP) ,central venous pressure (CVP) ,peak airway pressure (Ppeak) ,plateau airway pressure(Pmean ) at the time point of preoperative(T0) ,before infusion of protamine (T1) ,1 minute after infusion of protamine (T2) ,3 min (T3) ,5 min (T4) ,10 min (T5) ,15 min (T6) and 25 min (T7) were recorded .The level of venous blood thromboxane B2(TXB2) was detected .Results After infusion protamine ,the PAP ,PVP ,CVP ,Ppeak and Pmean of group A2 and group B2 are higher compared to group A1(P< 0 .05) and group B1(P< 0 .01) respectively ;Compared with preoperation (T0) ,the TXB2 in 4 groups increased obviously after infusion protamine (T2 to T7) (P< 0 .05) ;Compared with group A1 and group B1 ,the TXB2 of group A2 and group B2 increased more significantly (P< 0 .01) .Conclusion Patients with congenital heart disease after intracardi-al surgery with extracorporeal circulation use trace pump infusion protamine through the aortic root ,which have little effect on pul-monary circulation ,can significantly reduced TXB2 release compared with central vein administration ,it can avoid a high concentra-tion of protamine directly into the pulmonary circulation that can strongly stimulate the pulmonary vascular and tracheal smooth muscle .Especially in the CHD patients with PAH .