Twodimensional design of tunnel portal engineering has poor design accuracy and engineering quantity calculations due to the considerable distance between measurement crosssections and discrete application of the measurement data. Accordingly, a threedimensional automatic design software for tunnel portal engineering is developed based on the design process of tunnel portal engineering and the concept of informatized and intelligentialized design, integrating the functions of slope excavation, tunnel portal excavation and backfilling, tunnel portal structure generation, water cutoff trench layout, and quantity calculation. The application results reveal that the recommended method can improve the traditional tunnel portal design methods with better convenience and accuracy of the design results. Thus, this method provides the primary conditions for applying engineering information throughout the entire life cycle.