The common causes of venipuncture failure include unskilled technique and post-puncture operation errors may lead to venipuncture failure. 1. Unskilled technique: unskilled technique of puncture personnel and nursing staff, unfamiliar with the anatomy of the vein, too large or too small angle of the needle when injecting may cause venous puncture failure. If the force is too big or too small or the speed is too fast during the puncture, it may cause the vein wall to be punctured and the puncture fails. 2. Post-puncture operation error: The prolonged use of tourniquet after puncture results in insufficient venous blood supply and obstruction of venous return, thus leading to puncture failure. If the needle is not fixed properly when injecting, it will also cause the needle to swing from side to side in the lumen of the blood vessel, resulting in rupture of the vein wall and local bruising causing puncture failure, etc. Patients after venipuncture failure are recommended to undergo standardized treatment under the guidance of a doctor in a timely manner.