Positive urinary occult blood is divided into physiological causes and pathological causes. The former includes female menstrual blood contamination of urine, and the latter includes hemolytic disease, renal tumors, inflammation, and stones. 1. Physiological reasons: urine routine examination during menstruation, urine occult blood may be positive, after menstruation to review the urine routine. 2. Pathological causes: including hemolytic diseases, renal tumors, inflammation, stones and so on. Diseases causing intravascular hemolysis mainly include paroxysmal sleep hemoglobinuria, acute hemolytic disease, various viral infections, extensive burns and so on. Bleeding can also be caused by lesions in the kidneys that result in a positive urine occult blood test, commonly due to kidney tumors, inflammation, and stones. It is not recommended to look at some test results in isolation, only positive urinary occult blood can not be simply concluded as hematuria, it is recommended to carry out urine sediment microscopy, renal function test, blood routine, urinary ultrasound and other related examinations, under the guidance of specialists to determine the cause of the disease, to give targeted treatment.