Abstract Objective: To discuss the relationship between the normalized operation of central line insertion and catheter-associated blood stream infections. Methods: We analysed retrospectively the incidence of catheter-associated blood stream infection in 128 patients who had a central line inserted in the ICU from Feburary in 2009 to Feburary in 2010. From september in 2009 when we began to take the normalized operation of central line insertion, the 61 patients who were inserted through normalized operation belonged to the experiment group, while the 67 patients who were inserted through experiential operation before belonged to the control group. Then we compared the incidence of catheter-associated blood stream infection of the two groups. The normalized operation of central line insertion includes: 1.To prevent catheter-associated bloodstream infections doctors and nurses will choose a vein where the catheter can be safely inserted and where the risk for infection is small. 2. Clean our hands with soap and water or an alcohol-based hand rub before putting in the catheter. 3. Wear a mask, cap, sterile gown, and sterile gloves when putting in the catheter to keep it sterile. The patient will be covered with a sterile sheet. 4. Clean our hands, wear gloves, and clean the catheter opening with an antiseptic solution before using the catheter to draw blood or give medications. 5. Decide everyday if the patients still needs to have the catheter. The catheter will be removed as soon as it is no longer needed. Results: There were 5 cases of catheter-associated blood stream infection in the control group, while no such cases taken place in the experiment group. So the statistical  difference between the two groups is obvious. Conclusion: The normalized operation of central line insertion can avoid the catheter-associated blood stream infection effectively.