In general, urine and kidney function should be examined promptly in patients with suspected kidney disease. These tests can provide a preliminary understanding of the extent of kidney disease, but if the nature of the kidney disease is still not clear, a kidney biopsy must be performed to assist in the diagnosis. The easiest way to test urine is the “paper test” method. This method can only give a rough idea of the amount of various components in the urine, but cannot accurately determine the degree of hematuria and proteinuria. Therefore, in order to know the severity of the disease, nephritis patients should undergo a comprehensive and accurate examination. At present, the common methods are 1. urine red blood cell morphology analysis: This test is a special method to observe the number of red blood cells in the urine and morphological changes, which can accurately determine the degree of red blood cells in the urine and from which part of the urinary system, which is extremely important for clinical diagnosis of nephritis and observation of changes in the disease; 2. urine protein quantification: it can accurately grasp the leakage of 3, urine protein composition analysis: by determining the size of the molecular weight of protein urine, the degree of glomerular filtration membrane damage can be indirectly inferred; 4, urine osmolality: the concentration and dilution function of the renal interstitial tubules can be understood; in addition, there are some tests that can determine the enzymatic changes in urine, which can also help determine the severity of renal lesions, especially tubular damage. degree. Nevertheless, due to the wide variety of nephritis, the differences in clinical manifestations and blood and urine tests are not very obvious, and the various tests mentioned above are only peripheral indicators to indirectly infer the nature and extent of kidney lesions. Therefore, to accurately grasp the nature and severity of kidney lesions, only by means of kidney biopsy can be achieved. Renal biopsy is the abbreviation of renal biopsy histological examination. Since the biopsy tissue is obtained by puncture, we often refer to renal biopsy as renal puncture. To date, kidney biopsy is still one of the essential tools for diagnosing the nature and extent of kidney lesions and choosing the best treatment plan. The method is to take out a small strip of tissue from the kidney with a small puncture needle, and carefully study it through a series of modern scientific methods such as light microscopy, electron microscopy, immunology and molecular biology, and analyze it according to the characteristics of the lesions in the glomerulus, tubules, interstitium and small blood vessels in the kidney to identify which type of kidney disease it belongs to, its degree and regression, and to provide accurate information for treatment. With the development of modern medical technology, this technique has been commonly carried out in most hospitals.