Thrombo-occlusive vasculitis late ulcers painful, the correct treatment of ulcers can effectively shorten the treatment time. The treatment of vasculitis ulcers using the silkworm method is introduced as follows: The so-called silkworm method is to remove the necrotic tissue from the trauma surface in stages and batches day by day, the advantage of which is that it does not cause local trauma, and because this surgical operation is performed according to the form of silkworm, it is called the silkworm method. Now this method has been written into the textbook of “Chinese Medicine Surgery” and is widely used throughout the country. The nibbling method is suitable for the local treatment of gangrene of the toes or fingers, the dorsum of the foot above the metatarsophalangeal joint or the plantar and heel masses, before the local inflammation has completely subsided and before the collateral circulation has been established. It can make the necrotic tissues gradually subside, the ulcers gradually shrink, the pain is reduced, and it can promote the establishment of collateral circulation and increase the limb preservation rate to 96%. Our department has applied this method to clinical practice for more than 40 years, with clear efficacy in the treatment of lower extremity gangrene. Steps of the nibbling method: 1. Clear the local necrotic tissue by nibbling, together with anti-infection and Chinese herbal medicine treatment; 2. Remove the rotten bone and perform skin suturing, or perform punctiform skin grafting if skin suturing is not available. The operation characteristics of nibbling method are as follows: 1. principle: necrotic tissues should be removed in batches, healthy tissues should be preserved as much as possible to avoid unnecessary trauma; 2. indications: control local inflammation and edema, soften traumatic scabs; 3. sequence: distal, loose, bloodless and painless, exposed bone stumps should be removed first, and proximal, firm, bloodless and painful, buried bone severed ends should be removed later.