The invention provides a method for preparing sodalite by utilizing high-alumina fly ash. The method comprises the following steps: 1) subjecting the high-alumina fly ash to pre-desiliconization treatment so as to obtain desiliconized fly ash and desiliconized alkali liquid; 2) mixing the desiliconized fly ash with sodium carbonate and limestone and then successively carrying out calcination and dissolution so as to obtain a sodium aluminate solution; 3) subjecting the desiliconized alkali liquid, the sodium aluminate solution and the sodium chloride solution to mixing and homogenizing so as to obtain a homogenized slurry; and 4) subjecting the homogenized slurry to crystallization, and subjecting the obtained crystallized product to filtering, washing and drying so as to obtain the sodalite. The method provided by the invention uses industrial intermediates, i.e., the desiliconized alkali liquid and the sodium aluminate solution as raw materials to prepare the sodalite applicable to industrial application, and has the advantages of simple process, low energy consumption, low cost, and high utilization rate of the raw materials; meanwhile, the sodalite prepared by utilizing the method provided by the invention has the characteristics of high whiteness, fine granularity, uniform granularity, etc., lays a foundation for production of high-quality sodalite, and has great industrial popularization and application values.