The invention relates to a spherical large particle aluminum nitride powder preparation method, and belongs to the field of powder metallurgy. The spherical large particle aluminum nitride powder preparation method is characterized in that aluminum nitride powder, a binder, a sintering aid and a dispersing agent are mixed in an organic solvent to prepare a slurry, spray granulation is performed to obtain spherical aluminum nitride aggregate adopted as the granulating material, and then high temperature calcination and ball milling dispersion are performed to prepare the spherical aluminum nitride powder, wherein the sphericity of the obtained spherical aluminum nitride powder is 0.65-0.9, the particle size is 5-80 [mu]m, the apparent density is 0.85-1.1 g/cm<3>, and the tap density is 1.0-1.25 g/cm<3>. According to the present invention, the aluminum nitride powder prepared through the method has characteristics of high sphericity, uniform particle size and good fluidity, the preparation process is simple, the production cost is low, and the prepared powder can be used for thermally conductive plastic fillers.