The sustainable development of marine eco-economic systems is fundamental for ecological and marine economic systems. The present study used emergy analysis to develop a model and index system for marine eco-economic systems. We selected coastal and sea areas in China and used data from 2013 to examine sustainable development of the marine eco-economic system. The results show that the: (1) in 2013, total emergy of marine eco-economic systems of coastal provinces is 1.70×10²⁴ sej, and renewable resource emergy comprised the principal portion of emergy in China;(2) emergy density of different coastal provinces showed considerable differences, which were affected by regional marine resource reserves and economic development levels. The emergy currency ratio was high in the south of Shanghai and low in the north. The emergy yield ratio of marine eco-economic systems had high, middle, and low structures, and was predominantly composed of the middle structures; (3) marine eco-economic systems of China are based on a relatively high marine ecological capacity. However, the marine ecological capacity in some areas is lower than other regions,which influenced the balance of regional marine ecosystems.The environmental load ratio of marine eco-economic systems was high, indicating a more developed marine economy;(4) from the index of sustainable development, the integral sustainability of the Chinese marine economy is good, but there is a heavy environmental load ratio, and the lower marine ecological capacity of some areas could affect the sustainable development of the regional marine economy.