Varicocele is divided into two kinds: primary and secondary. I. Causes of primary varicose veins: 1. congenital absence of venous valves or incomplete closure of venous valves in the spermatic vein; 2. weak connective tissue around the vein; 3. lack of smooth muscle or elastic fibers in the vein wall; 4. dysplasia of the levator muscle; the left side is the most common (81% of the causes): 5. the left internal spermatic vein has a longer stroke than the right side; 6. the left internal spermatic vein converges into the ipsilateral renal vein at a right angle. The left internal spermatic vein is located in front of the sigmoid colon and is easily compressed by it; 8, the left renal vein passes between the abdominal aorta and superior mesenteric artery, and the pulsation of the two arteries increases the renal vein pressure, resulting in the obstruction of the reflux of the left internal spermatic vein and the formation of proximal clamp; 9, the left common iliac artery compresses the left common iliac vein, causing the obstruction of the reflux of the left spermatic vein and the formation of distal clamp. Secondary causes of varicocele: 1, peritoneal or retroperitoneal tumor compression; 2, renal tumor forming cancer thrombus in renal vein and inferior vena cava; 3, hydronephrosis compression; 4, ectopic vascular compression.