The invention relates to a method for preparing a fly ash porcelain granule, which comprises materials and proportions thereof and a production technical process, wherein according to the material proportions, 85 to 95 percent of fly ash, 1 to 10 percent of coal dust and 0 to 10 percent of clay are prepared into 1 to 2 percent of 0.5 to 0.05 percent combustion improver solution; the technical process comprises the following steps: stirring the materials to prepare a mixture; spraying a combustion improver solution to the mixture; rolling the mixture to prepare a porcelain granule ball blank; screening the blank and roasting the blank in a kiln for 1.0 to 1.5 hours; cooling the blank until the temperature is 600 DEG C and then taking the blank out of the kiln; and cooling the blank naturally to obtain the finished product of the fly ash porcelain granule. Because the mixture is doped with a small amount of the coal dust and the combustion improver solution agglutinates the mixture to form the porcelain granule ball blank, all inflammable components contained in the porcelain granule ball blank can be burnt sufficiently, is not only advantageous to improve the burning efficiency, reduce the cost, shorten the roasting time and improve the production efficiency, but also overcomes the situations that in the prior art, the fly ash porcelain granule has different colors and different hardness degrees, thereby providing a basic guarantee for the fly ash porcelain granule to be used in building decorative materials.