Men with blood in the urine may be caused by acute injury, urinary tract infection, urinary stones, urinary tract tumors, systemic diseases and other factors. 1. Acute injury: men’s lower body suffered an external blow, resulting in local damage to the urethra, in the process of urination will appear blood in the urine, accompanied by urinary pain. 2. Urinary infections: such as pyelonephritis, cystitis, etc., when the infection is more serious, the local tissue damage to the urinary tract, causing bleeding, which will lead to hematuria, accompanied by urinary pain, urinary frequency, urinary urgency and other symptoms. 3. Urinary stones: for example, bladder stones or ureteral stones, when urinating or changing position, the stones move, resulting in damage to the surrounding tissues, which will cause hematuria, and may be accompanied by pain in the lower back and abdomen, urinary frequency and other symptoms. 4. Urinary system tumor: for example, bladder tumor, etc., tumor surface tissue necrosis, causing bleeding, which will lead to hematuria, usually painless hematuria. 5. Systemic acute: for example, leukemia, hemophilia, thrombocytopenic purpura, etc., may cause hematuria. Men should pay attention to hematuria, and it is recommended to seek medical examination and treatment as soon as possible to avoid delaying the condition.