Objective: To investigate the anatomic characteristics and surgical treatment methods of the C5-C6 grade varicose of great saphenous vein (GSV). Methods: The clinical data of 69 patients with C5-C6 grade varicose GSV (84 limbs), who underwent surgery between August 2008 and September 2010, and were available for follow-up were analyzed. The patients were divided into deep vein stripping and deep vein plus superficial vein stripping groups, the skin flap necrosis rate, thrombophlebitis recurrence rate and clinical symptom relief rate after surgery between the two groups were compared. Results: There was no significant difference between the two groups in terms of sex, age and disease duration. Of the deep vein stripping group, skin flap necrosis was found in three limbs, thrombophlebitis recurrence occurred in seven limbs and the symptoms were completely alleviated in 21 limbs after surgery. Of the deep vein plus superficial vein stripping group, the skin flap necrosis was found in 38 limbs, thrombophlebitis recurrence occurred in one limb and symptoms were completely alleviated in 42 limbs. The skin flap necrosis rate of the deep vein plus superficial vein stripping group (84.44%) was higher than that of the deep vein stripping group (7.69%) (P＜0.01). The thrombophlebitis recurrence rate of the deep vein plus superficial vein stripping group (2.22%) was lower than that of the deep vein stripping group (17.95%) (P＜0.05). The clinical symptom relief rate of the deep vein plus superficial vein stripping group (93.33%) was higher than that of the deep vein stripping group (53.85%) (P＜0.01). The healing time of skin flap necrosis of the deep vein plus superficial vein stripping group was significantly prolonged compared with the deep vein stripping group (P＜0.01). Conclusions: The superficial veins have importance to the prognosis and survival of skin flap of patients with varicose GSV severer than C4 grade, so individualized treatment should be employed for those patients during operation.