Abstract： Objective To investigate the relationship of sealing catheter with different concentration of heparin sodium and obstruction after percutaneous insertion of subclavian venous catheters.Methods A total of 889 cases of tumor with percutaneous insertion of subclavian venous catheters were individed into two groups, group A was flushed with (50 U/ml) 5 ml heparin sodium before and after infusion,and group B were flushed with (50 U/ml) 5 ml heparin sodium before and after infusion.Results 5.55% (25/889) of catheter obstruction in group A were occurred and 1.13% (5/889) of catheter obstruction in group B were occurred, there wss signification difference between the two groups (P ＜0.05) .Conclusions There is an obvious relationship of sealing catheter with different concentration of heparin sodium and obstruction after percutaneous insertion of subclavian venous catheters.Flushing catheter with 125 U/ml heparin sodium can reduce thecatheter obstruction rate effectively.