The invention discloses a concrete interception device of a large-slope roof. The concrete interception device of the large-slope roof comprises a plurality of insertion plates and a plurality of fixing steel pipes, wherein the insertion plates are arranged at intervals and are parallel to the direction of a cornice, the fixing steel pipes are arranged in parallel and penetrate through all the insertion plates on the same slope correspondingly, the lower portion of each insertion plate is provided with a slot corresponding to steel bars of roof panels, and the upper portion of each insertion plate is provided with a through hole allowing the corresponding fixing steel pipe to penetrate through. The insertion plates for interception are placed stage by stage, vibrating rods can be used for vibrating, the situation that concrete is unrestricted under the action of gravity an naturally molded in the slipping state, and consequently a pitting surface and reinforcement exposure are caused can be avoided, and by means of the insertion plates, the concrete can be densely vibrated and well molded. Meanwhile, another insertion plates are arranged after the steel bars are distributed, through clamping and embedment between the insertion plates and the steel bars in the transverse direction and series positioning between the insertion plates and the fixing steel plates in the longitudinal direction, position stability of the insertion plates is effectively controlled, and meanwhile the effect that the insertion plates are perpendicular to the slopes is ensured.