The invention discloses a method for manufacturing an autoclaved flyash-lime brick by using an FCC (Fluid Catalytic Cracking) waste catalyst. The method comprises the following step: by taking the FCC waste catalyst, coal ash, thiourea filter residues (Ca(OH)2) as main raw materials, doping a proper amount of aggregate, performing raw material pretreatment, pressing molding and high-temperature high-voltage steam curing, thereby obtaining the autoclaved flyash-lime brick. The autoclaved flyash-lime brick can replace conventional clay red bricks, and is a novel wall body material which is greatly developed and applied in China. The autoclaved flyash-lime brick is manufactured by using the FCC waste catalyst safely and efficiently. Not only are local solid-waste treatment problems solved, but also farmlands can be saved, pollution can be reduced, and the environment can be protected; as a great deal of industrial waste residues can be utilized, the autoclaved flyash-lime brick is good in durability and relatively high in wall body strength, and has great significances of environment protection and waste utilization.