Objective To discuss the electrocardiogram(EKG)positioning method to the guiding role of determining the pipe length and the accuracy of operative localization in central venous catheterization procedure. Methods Chose 32 cases of tumor patients who had center venipunture.Use the catheter taken EKG data when cath-etering,and then given validation using postoperative chest X -ray or fluoroscopy.Judgment the sensitivity,specificity and disposable catheters success rate of the EKG positioning method.Results In the 32 cases of cancer patients, 30 patients had characteristic P waves,when the chest X -ray confirmed the superior vena cava or the junction with the right atrium,one case into the right atrium,when one case of non -P -wave in the subclavian after intravenous discounts tune into the tube after it confirmed the superior vena cava.Conclusion EKG positioning method with high accuracy in the deep venous catheter in the catheter tip positioning applications.The clinical applications are feasible.