Taking the 1T2R posture type parallel mechanism as the research object, a method for digital characterization and visualization model construction of topological structures by integrating screw theory and CAD technology is proposed. Firstly, in response to the demand for automatic generation of visualization models, a computer characteristic description code for topological structure is proposed to establish the mapping relationship between the feature code and the assembly features between CAD models of components. Secondly, based on the screw theory, various topological structures of mechanisms belonging to the same family as the 3-PRS mechanism are synthesized, and their computer feature descriptions are carried out to form a database of mechanism topological structures. Finally, a component library is established based on the required components for building the visualization model, and the dimensional characteristics, interface characteristics, and the orientation characteristics of the joint axes of each component are described by using the skeleton elements, laying the foundation for the future computer-aided kinematic performance analysis. On the basis of the above work, a 1T2R posture parallel mechanism type synthesis and topological structure visualization modeling software is developed by means of SolidWorks API interface technology, achieving the automatic generation of visualization CAD models that meet the requirements of computer-aided kinematic performance analysis.