The smell of urine may be caused by physiological factors, urinary tract infections, urinary tract tumors, diabetes and other factors. 1. Physiological factors: urine concentration, eating garlic, onions and other foods, taking B vitamins and other drugs, can lead to urine odor, in the elimination of the above triggers can be improved on their own, without the need for other treatments. 2. Urinary system infections: for example, cystitis, after the aggravation of the infection, the presence of purulent secretions in the urine, leukocytes and other substances, which can lead to urine odor, accompanied by pain in urination, urinary frequency, urinary urgency and other symptoms. 3. Urinary system tumor: for example, bladder tumor, tumor surface tissue necrosis, it will make the urine smell, may also appear naked eye painless hematuria, urination difficulty and other symptoms. 4. Diabetes: diabetes for a long time, may induce ketoacidosis, will make the urine appear obvious odor, usually rotten apple flavor, there will be weakness, polyuria, drinking and other symptoms. The smell of urine may also be caused by other factors, if there is a smell of urine and other abnormalities, but also ruled out physiological factors, it is recommended to go to the regular hospital for medical examination and treatment, to avoid delays in the condition.