With the purpose of optimizing the transportation industry structure and promoting its development, it is need to quantitatively evaluate the structure and propose the accurate and effective development strategy of transportation industry. The relations between the development of transportation and evolution of industry structure were observed from the perspective of traffic economy. A grey evaluation model was built for transportation industry structure of Ningbo based on the grey theory. Through the grey relational analysis method, the quantitative analysis for the transportation industry structure from 2011 to 2014 of Ningbo was conducted. According to the calculation results of the correlation degree, the grey correlation degree of waterway transportation, air transportation and urban traffic were large, which played a leading role in the development of traffic economy. The research results reveal that the structure system of transportation industry has been initially formed. But it also presents the characteristics of imbalance in industrial structure, multi-speed of development, and fragile industrial correlation and complementarity. Thus, three strategies were proposed to optimize the transportation industry structure of Ningbo: strengthening the interactions between the transportation and related industry, intensifying the cultivation of the transportation leading industry, paying attention to guide the development of air transportation.