China's many islands are similar in industrial structures, characterized by single structure, normally as fishing. This kind of traditional industrial structure based on resources is not good for the sustainable development in island economy. This paper, based on a case study on Changhai county, analyzes its industrial structure and features, indicates an unstable fishing production and lack of competitiveness. The second and third industries are laggard behind the first industry. According to the rules of industrial structure and the limit of gross resources, it is necessary to adjust its industrial structure in Changhai county. This paper presents strategies to the industrial transition, including increasing the industrial structures, developing new fishing and technical industries, and focusing on tourism. The third industry shall be developed very quickly, which could be as a reference for other islands.