Catheterization is divided into male and female catheterization, the following mainly introduces male catheterization, including preparation, position, disinfection, slippage, insertion and retention. 1. Preparation: Prepare disinfectant and cotton swabs in advance, ask the patient to wash the vulva, explain the purpose to the patient and obtain consent. 2. Position: take the supine position, stand on the right side of the patient, ask the patient to take off the pants leg of the near side, then cover the opposite leg, and bend the knees of both legs apart. 3. Disinfection: lay the treatment towel, the physician puts on gloves, uses disinfectant to clean the penis, wraps the penis with gauze and pushes the foreskin back to expose the urethral opening and coronal sulcus, etc., and disinfects the urethral opening as well as the glans and other parts of the penis. 4. Lubrication: Use paraffin oil to lubricate the catheter. 5. Insertion: Use hemostatic forceps to hold the catheter, and then gently insert it into the urethra, place the catheter about 20~25 cm, and then insert it for a certain distance after seeing urine. The balloon is filled with 10~15 ml of water. 6. Retention: according to the condition of the specimen is retained, and then cleaned up with. Catheterization should be completed by professional medical personnel, if you need catheterization, please consult a professional hospital.