Infrastructure construction and economic growth are dynamically interactively theoretically correlated, however, for the poor area under external assistance, the relationship between the two has actuality and specialty. Three Gorges Reservoir Area has historic poverty feature but is largely supported by external funds. The empirical analysis is conducted on infrastructure construction and economic growth in 15 counties in Three Gorges Reservoir Area during 2000-2018 by using panel vector autoregressive model and the results show that the infrastructure construction in Three Gorges Reservoir Area has dynamically boosting effect on economic growth, while on the contrary, it is not obvious, the two have unidirectional interactive relationship. In impulsive response analysis, the interactive effect of the two demonstrates “inverted-U type” feature, and the time lag effect of the two shows “reverse-J type” feature. In present stage, the interactive effect of infrastructure construction and economic growth in Three Gorges Reservoir Area is not significant. Before the termination of a series of assistance policies, this paper suggests to increase endogenous interaction between infrastructure construction and economic growth in the Area from two perspectives, on the one hand, the timetable for the exit of all kinds of assistance policies in different stages in order should be clarified, on the other hand, the infrastructure construction funds should be jointly developed by all counties and districts in Three Gorges Reservoir Area.