Men themselves have kidney stones, no strenuous exercise but blood in the urine, may be due to kidney stones combined with infection, kidney stone malignant lesions. Kidney stones cause blood in the urine, usually because the stones cause mucosal damage, infection, stone malignant lesions caused by the first reason can be ruled out if there is no men do not have strenuous exercise. 1. Kidney stones caused by infection: If kidney stones cause infection in the urinary system, it will generally make the stone growth speed up, which will lead to mucosal redness, congestion, edema, and blood in the urine. 2. Malignant lesions of kidney stones: If kidney stones stay in the male body for too long, they may cause malignant lesions, i.e. lesions of the renal pelvis, renal calyx and other mucous membranes, which will lead to blood in urine. It is recommended that male patients should consult a doctor in time for examination and take corresponding treatment measures after clarifying the cause of the disease.