Varicocele in children may be related to anatomical causes of the testicular veins themselves, or it may be caused by compression of the left renal vein. Some patients are asymptomatic and some may have scrotal discomfort. 1. Anatomical reasons: the left testicular vein is longer than the right one, which makes the hydrostatic pressure of the vein on the left side high; if the testicular vein valves are lacking, it will also cause the pressure of the vein to rise significantly during reflux. 2. Left renal vein compression: Nutcracker syndrome, the left renal vein is close to the descending aorta in the front and the superior mesenteric artery in the back, which is easy to be compressed, and the elevated venous pressure can be transmitted to the testicular vein, which will ultimately cause dilatation. There may be other causes of varicocele in children, which need to go to regular hospitals and be treated under doctor’s guidance so as not to delay the condition.