Under normal circumstances, there are no red blood cells in urine. In medicine, the patient’s urine is centrifuged and precipitated and then examined by microscope, if there are more than 5 red blood cells in each high power field of view, it is called hematuria. If only under the microscope to find out the red blood cells, but the eyes can not see blood in the urine, called microscopic hematuria; if the eyes can see the urine is “wash water” or with blood color, and even in the urine of blood or blood clots, called the naked eye hematuria. More than 95% of hematuria is due to diseases of the urinary tract itself, including glomerular diseases (acute nephritis, acute-progressive nephritis, membranoproliferative nephritis, membranoproliferative nephritis, focal glomerulosclerosis, etc.), renal cysts, stones (renal, ureteral, bladder and urethral stones), prostatic hyperplasia, urinary tract infectious diseases (tuberculosis, pyelonephritis, vesicoureteral inflammation, prostatitis) and tumors (renal, ureteral, bladder and urethra), and urinary tract infectious diseases (tuberculosis, pyelonephritis, cystitis, and prostatitis). Ureteral, bladder and prostate tumors are the most common. Other disorders such as blood clotting abnormalities (idiopathic or drug-induced thrombocytopenia, hemophilia, scurvy, etc.), systemic diseases (cataracts, leukemia, systemic lupus erythematosus, dermatomyositis, leptospirosis, epidemiological hemorrhagic fevers, etc.) can also cause hematuria. Among the countless causes of hematuria, we should be alert to a kind of painless hematuria, because this kind of hematuria is often a signal of malignant tumor of urinary tract. In the early stage of renal pelvic tumors, there will be painless hematuria throughout the naked eye, which may be intermittent or persistent. Hematuria in renal tumors mostly occurs when the tumor invades the renal pelvis, mostly in the middle or late stage of the tumor, and hematuria often occurs suddenly. When the tumor invades the nerves of the peripheral tissues of the kidney, the pain in the lower back is felt. Bladder tumors and ureteral tumors mostly occur in men over 40 years old, and the main symptom is intermittent spontaneous painless hematuria, i.e., hematuria is sporadic, more or less, hematuria can last for several days, or it can be absent for a longer time. Patients often mistakenly believe that the disease has been cured. The earlier the bladder tumor is detected, the better the treatment effect. Prostate cancer is characterized by hematuria at the end of urination, accompanied by obvious urinary frequency, urinary urgency, urinary pain, urinary difficulty, urinary retention, etc. The enlarged prostate gland can be felt by anal finger test. In short, painless hematuria is the urinary system, especially bladder tumors, an early important signal, especially in the middle-aged and elderly people can not be ignored, once the first time to find painless hematuria, should go to the hospital to find urological specialists for detailed examination of a clear diagnosis. In order to determine the site where hematuria occurs, doctors mostly adopt the following examination methods: 1. Repeatedly looking for cancer cells in urine, such as finding cancer cells in fresh urine, which will help the diagnosis of bladder cancer. 2.Radiological examination, including abdominal plain film, intravenous pyelogram and renal angiogram. 3.B-type ultrasonography: it helps to diagnose polycystic kidney and kidney tumor. 4, Radionuclide examination, commonly used in renal scanning, is helpful for the diagnosis of renal tumor. 5.Cystoscopic speculum examination can directly find out the site of bleeding and its nature. 6.Other examinations: CT scan or MRI scan can also be done for those who cannot determine the source of hematuria or suspected to be from the kidney. For this reason, malignant tumors of the urinary tract cannot be easily ruled out in a patient with painless hematuria until a cause is found.