The possible causes for the occurrence of carnal hematuria in men are: 1. Infection of the urinary tract. In urinary tract infection, the mucosa of the urethra becomes congested and edematous, resulting in hematuria or microscopic hematuria during urination, usually accompanied by frequency, urgency, painful urination and other discomforts, which can gradually disappear after anti-infection treatment. 2, urinary tract stones. The presence of stones can cause bleeding by stimulating the surrounding mucosa. In addition, it is accompanied by acute pain in the lower back and abdomen, which is usually more intense. After diagnosis, extracorporeal shock wave lithotripsy is needed to cure hematuria. 3. Urological tumors, mostly seen in elderly patients, usually do not have any pain, urinary frequency, urinary urgency and other symptoms. However, when the tumor gradually increases in size and causes pressure symptoms, it may show symptoms of urine volume becoming less or local pain. In this case, further ultrasound or CT is needed to confirm the diagnosis, and if the presence of tumor is confirmed, surgery is needed to completely cure the problem of hematuria.