The invention provides a method for preparing petroleum fracturing propping agent by utilizing high-alumina fly ash. The method comprises a smashing step, a roasting step, a magnetic separation step, a burdening step, a granulation step, a sintering step and a cooling step, and comprises the following specific steps of: (A) smashing the high-alumina fly ash for later use; (B) feeding the processed material into an atmosphere furnace and calcinating the processed material; (C) performing magnetic separation and deferrization on the calcinated high-alumina fly ash; (D) feeding the high-alumina fly ash subjected to magnetic separation and deferrization and various auxiliary materials into a jet mill, fully mixing and smashing the high-alumina fly ash subjected to magnetic separation and deferrization and the various auxiliary materials, and then performing granulation treatment on the mixture in a disc granulator, thereby obtaining a green body; (E) sintering the green body in a rotary kiln, and naturally cooling the sintered green body, thereby obtaining a high-strength petroleum fracturing propping agent product. The method provided by the invention is simple in process; adopted raw materials are generally solid wastes and are low in cost and wide in source, so that the problem of reusing fly ash solid waste resources is mainly solved, and the method is environmentally-friendly and has good economic benefits ad social benefits.