Abstract: Coordinating the infrastructure construction is a clear requirement of the Report of the 20th National Congress of the Communist Party of China, where the coordinated development of “new” and “old” infrastructure is the key to high-quality economic development in China. Based on identification of the production externalities of “old infrastructure” and the network externalities of the “new infrastructure”, breaking through the static research frame, this paper studies the structural change effect of infrastructure investment on the path of economic growth. It finds that the short-term stimulus effect of “old infrastructure” is stronger than that of the “new infrastructure”, while the long-term economic stimulus effect and innovation incentive effect of the “new infrastructure” are obviously stronger than that of the “old infrastructure”. Meanwhile, “term constraint” is the key variable for the government to set the time point of the structural transformation of infrastructure investment. Government concerning more on the short-term economic growth target with less policy attention period often delays the time point of the structural transformation of infrastructure investment, which leads to the “step down” phenomenon of economic growth however. The empirical results further verify that “old infrastructure” has given full play to production externalities in the early stage of economic growth, whereas the incentive effect of “old infrastructure” on economic growth and innovative development is significantly weakened. While, the incentive effect of “new infrastructure” on economic growth and innovative development is significantly enhanced. Therefore, the government should combine the relative changes of marginal output of “new” and “old” infrastructure, adapting to local conditions, to promote the transformation of “new” and “old” infrastructure as soon as possible, and to coordinate the effective improvement of economic quality and reasonable growth of quantity.

Key words: new infrastructure, old infrastructure, term constraint, economic growth, innovative development