Submicron spherical alumina powder and preparation method thereof

The invention discloses submicron spherical alumina powder and a preparation method thereof, and is characterized in that the preparation method comprises the following steps: step 1, adding pure water and an alcohol organic matter into a reaction kettle, stirring to prepare a mixed solution A, and heating the mixed solution to 75-80 DEG C; 2, aluminum oxide powder is added into the mixed solution A to be stirred for 3-5 min, 0.1-2% of a silane coupling agent is continuously added into the mixed solution A to be stirred for 1-5 h, a mixture B is obtained, the mass ratio of aluminum oxide to the mixed solution A is 1: 1, and the median particle size is 0.1-10 micrometers; 3, standing and settling the mixture B for 5-72 hours, and removing supernatant liquid to obtain a precipitate C; 4, adding 98% concentrated sulfuric acid into the sediment C, and soaking for 72-120 hours to obtain a mixture D, wherein the mass of the concentrated sulfuric acid is the same as that of the sediment C; 5, the mixture D is taken