The traditional nasal dacryocystorhinostomy (DCR) was pioneered by Toti in 1904. The dacryocystorhinostomy is a procedure in which a new channel is created between the lacrimal sac and the nasal cavity to replace the obstructed nasolacrimal duct in order to drain the tears. The newly created tear duct can eradicate the patient’s overflow of tears and pus. During the surgery, an incision is made in the skin near the medial canthus, the tissue is separated to the lacrimal sac fossa, a bone hole is made, and part of the lacrimal sac and nasal mucosa are removed so that tears and secretions can enter the nasal cavity through the new drainage channel. In 1914, Kuhut improved it by suturing the lacrimal sac mucosal flap to the periosteum, and in 1920, Ohm improved it again by suturing the edges of the lacrimal sac wall incision to the nasal mucosal flap, and the method became definitive and widely used in clinical practice. The main postoperative complications affecting the results of external lacrimal sac nasal anastomosis are anastomotic closure and common lacrimal duct obstruction, the causes of which are anastomotic mucosal edema, blood clot blockage and scar and granulation tissue formation, tissue scar and granulation formation are mainly due to fibroblast proliferation and extracellular matrix biosynthesis such as collagen. Many domestic scholars have also made many improvements to the procedure, simplifying the surgical procedure, reducing intraoperative bleeding, shortening the surgical time, and increasing the success rate of the procedure, as well as making it simpler and easier to perform. For example: pay attention to the position of the bone hole, the size of the design; do not cut the inner canthal ligament during surgery, or cut only half the width of the inner canthal ligament, do not interfere with the lacrimal sac pump activity caused by the orbicularis oculi muscle; try to make a large lacrimal sac mucosa, nasal mucosa anterior flap, only the nasal mucosa and the anterior flap of the lacrimal sac need to be sutured, and only the posterior flap is well docked, not sutured, avoiding the deeper position of the operation, shortening the operation time; when suturing the anterior flap The anastomotic flap is suspended in the nasal periosteum or suspended by skin sutures; the intraoperative use of the antiproliferative drug mitomycin (MMC) helps to keep the osteoplastic hole open and improve the cure rate; the placement of a rubber drainage tube at the blind end of the lacrimal sac also has a supportive effect, preventing the formation of adhesions and clots in the anterior and posterior mucosal flaps, which greatly improves the success rate of surgery; the combined annular artificial lacrimal duct is left in place, etc. With the improvement of clinical technology, the success rate of external nasal lacrimal sac anastomosis reaches more than 90%. As a classical procedure, external nasal lacrimal sac anastomosis has been widely used and its efficacy has been confirmed after years of clinical practice and improvement, and it has advantages that cannot be replaced by other treatment methods for chronic dacryocystitis and nasolacrimal duct obstruction.