Nephritis is a general term for many types of kidney diseases. The principles and methods of treatment for different types of nephritis are very different. If it is not clear what kind of nephritis a patient is suffering from, no international ace nephrologist can give a real scientific treatment to this patient. Therefore, to clarify which kind of nephritis a patient is suffering from is the fundamental guarantee for the correct treatment of nephritis in clinical practice. Since kidney biopsy can clarify which kind of nephritis a patient is suffering from, it becomes a navigation light for proper treatment of nephritis and prolonging the life of nephritis patients. It is necessary to perform kidney biopsy not only for all kinds of glomerulonephritis, but also for all kinds of tubulointerstitial nephritis, and for kidney damage caused by various rheumatic immune diseases. Renal biopsy is also necessary for renal damage caused by allergic purpura and other kinds of vasculitis. By performing various advanced techniques of pathology, immunology, molecular biology and other examinations on the kidney tissues of patients, we are able to comprehensively analyze and grasp the nature of kidney lesions in patients with nephritis. Therefore, we overcome the blindness of treating headache and foot pain, and can make our kidney disease treatment effect reach the international advanced level. Our research in recent years has found that nephritis is partly caused by infection and partly caused by food allergens. The most common causes of nephritis are beef, milk, eggs, shrimp, crab and peanuts, and we check these food allergens when we do kidney biopsy on patients, and after the examination, we can tell patients what food allergens cause their nephritis, which plays an important role in treating nephritis and preventing its recurrence.