The invention discloses a high-temperature sealing type two-lug support plate self-locking nut, which comprises a nut body and a sealing cover, wherein the sealing cover is arranged on the outside of the nut body, the nut body comprises a support plate, a closing section and threads, the threads are arranged in the nut body, the bottom of the support plate is provided with a sealing cushion, a sealing ring is sheathed on the outside of the closing section, and the sealing ring and the sealing cushion are respectively made of high-temperature and low-temperature resistance silicon rubber. The self-locking nut has the advantages that the support plate is additionally arranged on the common two-lug floating self-locking nut, the special silicon rubber ring and the sealing cushion are adopted, and the sealing cover, the sealing ring and the sealing cushion are used in a matching way, so the structure is reasonable, the strength is higher and more stable when the self-locking nut is connected with a box body, and the installation reliability is greatly improved; meanwhile, the vibration resistance performance, the loose resistance performance, the high-temperature and low-temperature resistance performance and the corrosion resistance performance are better; and the guarantee is effectively provided for hydraulic systems, pneumatic systems and oil line systems in the fields of aviation, aerospace, ships, railways and the like, the economic benefits and the social benefits are better, and the self-locking nut can be widely applied to the industry of mechanical equipment.