Abstract: In this paper, focusing on the main structural characteristics and material properties of large guide rails with high-precision complex cross-sections, a process route covering four stages of guide rail forming including blank preparation, rough machining, medium-frequency quenching, and finish machining is established. Based on engineering cases of typical deformation problems encountered during actual machining, the influencing factors of different deformation issues are systematically analyzed; seven root causes are identified and corresponding control measures are proposed. By means of improved design of combined tooling, design and analysis of measurement systems, and optimization of machining parameters and process conditions, the machining deformation and associated risks of guide rails are effectively controlled, and the machining accuracy is ensured. A foundation is thereby laid for the application of virtual axis technology in large guide rails with high-precision complex cross-sections.