The work aims to clarify the status quo of China's metro line identification color design, find out the existing deficiencies, and propose new design strategies to better adapt the line identification color to the large-capacity rail transit situation. Firstly, relevant academic literature and existing practice were discussed; Secondly, the metro line identification colors that have been put into use in various cities in China were collected and sorted out, and the chromaticity properties of the colors were analyzed according to the Munsell system; Then, the questionnaire was used to explore the influence of the chromaticity attribute of the metro line identification color on its comfort. The basic principles and corresponding implementation methods of the current Chinese metro line identification color design practice were explained. Its design appeals were summarized into two levels of function and empowerment, and its six internal dimensions were sorted out. The readability and comfort rules of colors were found. In the design of metro line identification colors, the potential influence of color readability is often ignored, and it should be taken as an important consideration in relevant design practices. The comfort of metro line identification colors is affected by its lightness contrast; Based on this, a color design strategy proposed for the complex subway network is to maintain the color order of the subway information interface with both recognition and comfort.