The invention provides an ultra-high-temperature sealing coating powder material capable of being used at a temperature of 1200 DEG C and above, a coating and a preparation method thereof, and belongsto the technical field of thermal spraying. The material is composed of the three main components of SiC, Si and BN; the raw materials in the form of a powder separately are prepared into composite powder with different granular structures through a plurality of agglomeration processes; the sealing coating is prepared through thermal spraying, pressing sintering-brazing and other processes; the highest use temperature can reach 1350 DEG C, and is increased by more than 150 DEG C compared with the use temperature of the existing high-temperature sealing coating; and the coating is high in matching performance with CMC and other ceramic matrix composite materials, capable of adequately exerting the advantage of high-temperature resistance of the ceramic matrix composite materials, and widein application in a new generation of aero-engines and gas turbines.