The utility model provides a fabricated firewall which comprises a plurality of foundations, a plurality of vertically-arranged supporting columns, a plurality of wall beams and a wall top beam with first grooves formed in the bottom. The foundations are of a pouring cup type structure, and each supporting column is sequentially composed of a base column and a middle column or a side column from bottom to top. The two opposite side faces of each middle column are provided with H-shaped grooves used for mounting the corresponding wall beams. One side face of each side column is provided with a second groove. The two ends of each wall beam are connected with the middles of the two adjacent supporting columns respectively. The two ends of the wall top beam are further connected with the column tops of the two adjacent supporting columns respectively. The fabricated firewall further comprises a wall board connected with the outer walls of the supporting columns. The fabricated firewall is convenient to construct, the integrity of the supporting columns is improved, mounting convenience and node integrity are guaranteed, the number of nodes is decreased, the mounting processes are simplified, the safety and the reliability of the overall structure are improved, the working efficiency is improved, the construction period is shortened, and on-site safety and civilization construction management is facilitated.