Kidney biopsy, short for renal biopsy, is an important means to obtain pathological specimens of kidney, which is an important basis for diagnosis of kidney disease, selection of treatment plan and judgment of prognosis. The revision rate of clinical diagnosis of disease after kidney biopsy reaches about 35%, which indicates that the combination of pathology and clinical diagnosis is significantly better than the clinical diagnosis alone, and the conclusion is more reliable, which shows that kidney biopsy has a very important significance. For patients with nephrotic syndrome, as long as there are no contraindications (such as obvious bleeding tendency, severe hypertension, psychosis or uncooperative, isolated kidney or small kidney) are suitable for kidney biopsy. But does not every patient without contraindications to renal biopsy need a renal biopsy? It is not necessary. For example, in children, because 80% of the pathological types are microscopic nephropathy, hormone therapy is sensitive, and hormone therapy is often used directly in clinical practice, and most of them can be cured, like these patients can not do renal biopsy. However, in children who are not sensitive to hormones or have atypical clinical symptoms or frequent relapses, renal biopsy is still needed before starting other treatments such as cyclophosphamide or cyclosporine. Renal biopsy should be considered in patients over 10 years of age with combined hypertension, renal insufficiency, or sarcoid hematuria. In adults, renal biopsy is advocated for primary nephrotic syndrome, which is important for clear diagnosis, guiding treatment and determining prognosis. For patients with clear secondary etiology, renal biopsy can be withheld. However, in recent years, with the widespread development of renal biopsy, the improvement of biopsy technology and success rate (up to 95% or more), the complications of renal biopsy have significantly decreased, and the prognosis is increasingly suggestive, therefore, renal biopsy is advocated for the diagnosis of patients with nephrotic syndrome.