Hematuria is very common in clinical practice and can be recognized as hematuria when the urine red blood cell count is >8,000/ml or 5/HP on microscopic examination, which can be divided into two categories: glomerular hematuria and non-glomerular hematuria based on morphological examination of urine red blood cells by phase contrast microscopy or red blood cell volume distribution curve. The former shows two or more polymorphic changes, with an aberration rate of >70% (some scholars believe >80%), especially the budding type ≥5%, mainly caused by various glomerular diseases; the latter is mainly caused by; infection, stone, tumor, vascular malformation, trauma, etc. The need for renal puncture biopsy in patients with persistent microscopic hematuria has been controversial, but it is now recognized as a strong independent predictor of increased risk of end-stage renal disease (ESRD) in adolescents, and it is advocated that renal puncture biopsy should be actively performed for definitive diagnosis and timely treatment. Although it is advocated that such patients should undergo renal biopsy, it is not possible or necessary in practice to perform renal biopsy in all such patients. Renal biopsy should be actively considered in patients with persistent microscopic hematuria with (1) microalbumin (urinary albumin/creatinine ratio >30 mg/g or 24-h urinary self-protein quantification >30 mg/d or urinary albumin excretion rate >20ug/min) or proteinuria (urinary protein quantification >0.3 g/d) at initial examination or during follow-up; (2) episodes of carnitic hematuria during the course of the disease; (3) patients with hypertension; (4) mildly reduced renal function, i.e., eGFR 60-90 ml/(min・1.73m2) or mildly elevated blood cystatin C; (5) elevated blood IgA levels or high IgA/C3 ratio; (6) prospective donors of transplanted kidneys; (7) married infertile women who need to evaluate the effect of pregnancy on renal pathology; (8) familial aggregation; (9) with hepatitis B virus carriers; (10) with evidence of interstitial renal tubular damage, such as elevated urinary NAGase, urinary lysozyme, urinary B2 microglobulin, low urinary specific gravity, nocturia, abnormal urinary acidification function, and acute. Those with positive new biological markers of kidney injury (NGAL, KIM-1, IL-18, etc.). Of course, glomerular hematuria must be identified before renal biopsy and ultrasound to exclude left renal vein compression syndrome.