Indwelling needles may cause infection. The indwelling needle, i.e. cannula, is suitable for long-term infusion, first aid, critical patients, etc. It can reduce the pain of repeated puncture of the patient and reduce the workload of healthcare personnel, however, improper operation or improper care may also cause the adverse consequences of infection. As the hose of the indwelling needle will cause irritation to the blood vessel for a long time, it may cause mechanical phlebitis, and if the indwelling needle is not replaced in time with a new one, the dressing sticker or improper care, it may also cause bacterial infectious phlebitis, and the stimulation of the medication of the long term infusion may also cause pharmacological phlebitis or thrombophlebitis. In order to prevent the occurrence of the above phenomena, health care workers are required to observe the patient’s puncture site more often, the correct disinfection, tube sealing, timely replacement of indwelling needles, to ensure that the use of time is not more than 3 to 5 days, the correct care of indwelling needles can prolong the use of time, which helps to eliminate the adverse effects. Patients should also actively observe the local situation during the use of the process, if the site of the indwelling needle appears red, swollen and painful, should promptly inform the doctor, usually in daily life to ensure that the local clean and dry, avoiding the puncture site stained with water.