An indwelling needle is an infusion tool that can be left in a blood vessel, which can effectively reduce the number of venipunctures. An indwelling needle is an infusion tool often used in clinical practice, and is mainly composed of several parts, such as a soft catheter, a stainless steel needle core, and a plastic needle holder. When the indwelling needle is used, it is necessary to puncture the catheter and the needle core together into the blood vessel, when the catheter enters the blood vessel and withdraws the needle core, and finally only need to leave the soft catheter in the blood vessel for infusion. Because the indwelling needle is left in the blood vessel for a longer period of time, it can effectively reduce the number of venipunctures and alleviate the patient’s pain, as well as fear and agitation. The indwelling needle can usually be retained for about 7 days, but in actual clinical work, the needle is usually replaced once in about 72~96 hours to avoid infection caused by too much time. The indwelling needle is a kind of infusion tool, need professional health care workers to puncture, do not use privately, in order to avoid adverse consequences.