With the acceleration of China’s urbanization, the functions and benefits of mega-projects are required higher. With the deepening ofthe Silk Road Economic Belt and the 21st-Century Maritime Silk Road, the quantitative evaluation of multinational investment projects will help strengthen cross-border communication among gov-ment, society and enterprises, which provide a basis for mutual trust. This study empirically analyzes and evaluates the impact of mega-projects on carrying capacity of cities, by using the DID method based on the panel data of 15 cities in China from 2000 to 2013. The results show that the construction and operation of the first-line project of the West-East gas pipeline has a significant positive impact on the improvement of carrying capacity of cities along the line. However, the degree of impact on three di-mensions is slightly different. The impact on the social carrying capacity is the greatest, then the ecological and economic carrying capacity. Therefore, the decisions of do-mestic mega-projects should be unified with urban planning to promote the sustain-able development of China’s economy and social. The investment of mega-projects abroad should also be coordinated with the carrying capacity of host cities, in order to enhance the competitiveness and creativity of Chinese multinational mega-projects investment.