The sloping plate in the pitched roof has the properties of both horizontal plate and vertical wall, which is quite different from the plate in bearing force, and has a great influence on the overall stiffness, internal force and index of the structure, as well as on the bearing force of the beam connected with it, the reinforcement of beam-slab members is controlled by tension bending.Combining with the requirement and calculation principle of pitched roof modeling in PKPM software V4.3, this paper introduces several methods of roof modeling in software, and compares and analyses the results of five examples, it is expounded in detail that the pitched roof slope plate should be correctly modeled in the calculation, and the necessity of its participation in the whole calculation should be considered.The influence of slope roof on structural stiffness, internal force and design index is very different, especially on the internal force and reinforcement of the beam connected with the inclined plate. The influence of slope roof on structural stiffness, internal force and design index is very different, especially on the internal force and reinforcement of the beam connected with the slope plate. This paper analyzes the limitation of calculating the internal force and the reinforcement of slope slab according to the projection plane by using PMSAP software to do the stress analysis of the slab and calculating the reinforcement of the slab. It provides a reference for designers to carry out this kind of engineering design.