Left renal vein compression syndrome, also known as nutcracker phenomenon, is a phenomenon of left renal vein hypertension caused by obstruction of renal venous blood flow return after mechanical compression of the left renal vein between the abdominal aorta and superior mesenteric artery. In the diagnosis, attention should be paid to the differentiation of hematuria caused by urinary stones, infectious disorders, congenital malformations, idiopathic hypercalciuria, trauma, tumors, etc. Urinary stones, congenital malformations, trauma, and tumors each have their own specific sonographic manifestations, which can be easily excluded. In particular, do not ignore the comprehensive judgment of clinical manifestations and laboratory tests to avoid delaying the diagnosis and treatment. In patients with left renal vein compression syndrome, asymptomatic hematuria and upright proteinuria do not require special treatment, and the development of the disease should be observed on follow-up. With age, the symptoms may improve with the increase of fat and connective tissue at the angle between the superior mesenteric artery and the abdominal aorta or with the establishment of collateral circulation, and the stasis may be relieved. If left renal vein hypertension persists and hematuria and proteinuria worsen, left renal vein stent implantation or renal vein shunt is feasible.