This chapter presents an intelligent AutoCAD plug-in for railway alignment design, integrating an improved adaptive dynamic programming algorithm, multi-objective optimization, and LLM-driven interaction. The modular architecture includes base data handling, preprocessing, alignment optimization, and multi-factor evaluation. Key innovations involve automated horizontal/vertical alignment generation, dynamic parameter adjustment, and synchronized visualization. Validated on a 108 km high-speed rail project, the tool reduced costs while ensuring compliance. A locally deployed LLM enables natural language commands (e.g., radius adjustments), real-time standard queries, and automated reporting. The plug-in supports diverse data formats (DXF, CSV) and operates efficiently on standard hardware. By combining algorithmic optimization with AI-driven interaction, it significantly enhances design efficiency, flexibility, and decision-making, advancing intelligent railway engineering.