When lymphatic filariasis causes inflammation of the lymphatic vessels and thickens the walls of the vessels, the lymphatic vessels from the intestinal trunk to the thoracic duct are dilated, the valves in the vessels are not fully closed, resulting in a dynamic obstruction and a blockage of the lymphatic fluid, which increases the pressure in the lymphatic vessels and ruptures at the weakest point. The common site of rupture is at the fornix of the renal pelvis and can produce a pelvic-lymphatic fistula. Prevention methods: census and treatment: organized and planned census of people over 1 year old in endemic areas, where microfilariae positive patients with or without symptoms, or microfilariae negative but with a typical history and signs of filariasis, should be treated generally, in filariasis, the implementation of census and treatment in highly endemic areas combined with universal (over 5 years of age) to take ethamazine or ethamazine salt, the dose of ethamazine for all people is, Bangs of filariasis 3g therapy (course of 3 or 5 days) or 4.2g therapy, and 0.5 to 1.0g for Malayan filariasis, 1 or 2 times divided, and repeated once in the second year. Cut off the transmission route: mainly mosquitoes, master the “extermination early, extinguish small, extinguish” principle, mosquito areas, focusing on the majority of rural areas, improve environmental health, clean animal sheds, fill in depressions, in places with more mosquitoes, with drug residual spraying, combined with agricultural production and pest control measures to control the larvae in the rice fields.