Abstract: In order to solve the decision-making optimization of main technical standards of the railway, this paper proposed a decision-making method based on case base. Through collecting a large number of existing railway decision cases, analyzing the influencing factors and action mechanism of the main technical standards of the railway, the paper extracted the main factors, divided the influencing factors into different attribute units, designed the rules of inputting into the database by the relationship between attribute units and main technical standards. The case base of main technical standards for lines based on GIS was established. Taking the newly built Tianshui-Longnan Railway as an example, the method was validated. The main technical standards of the line were selected by query sentences, which improved the scientific nature compared with the traditional method.