Under the background of the national strategy of a country with strong transportation network, the construction of transportation infrastructure urgently needs to be guided by new infrastructure, new urbanization initiatives and major projects to meet the requirements of smart transportation in the new era. As the main body of professional talent cultivation, universities should closely align with national strategies and industry demands, encourage the cross-disciplinary integration of transportation engineering with other subjects, promote the specialization of transportation engineering towards intelligent and information-based directions, and systematically reform the postgraduate training mode. This article first points out the challenges faced by postgraduate students in transportation infrastructure from both industry and university perspectives. Starting from the existing problems in the current training system, the article summarizes the four core competencies that postgraduate students in transportation infrastructure should possess: knowledge iteration ability, engineering practice ability, technological innovation ability, and international adaptation ability, focusing on theoretical knowledge, practical abilities, innovative thinking, and international perspectives. Based on this, the article proposes a reform plan for the training mode for postgraduate students in the cross-disciplinary direction of smart transportation infrastructure, with the core goal of improving the quality of postgraduate education. The plan includes curriculum systems, training modes, and cross-disciplinary integration as the main measures, with management methods, mentor teams, and practical platforms as a solid foundation to ensure the effective implementation of the reform measures. Three Supports and Three Guarantees are organically linked to jointly improve the quality of postgraduate education in this field, forming the concept of the reform of the training mode for postgraduate students in the cross-disciplinary direction of smart transportation infrastructure. Finally, relying on the practical exploration case of the School of Transportation Science and Engineering at Harbin Institute of Technology, the article introduces a series of achievements in international education, cross-disciplinary integration, and school-enterprise cooperation, providing a positive and reference model for the construction of the training mode for postgraduate students in the cross-disciplinary direction of smart transportation infrastructure.