Zhoushan City is the only prefecture-level city that is compcsed of islands on the sea; it possesses the advantage, such as natural islands, sea superiority, and rich tourism resources. Due to unique geographical unit and landscape, the island tourist industry develops very quickly. The influence of the tourist industry on the economy in Zhoushan Islands is analyzed by adopting path analysis model. The result shows that the tourist industry Zhoushan promotes the fast development of the economy in Zhoushan. The main source for the GDP of the tertiary industry of Zhoushan is the income from the tourist industry. The conclusion could be drawn that the tourist industry has already become the leading industry in the development of the economy in Zhoushan, and played a positive and important role in the social development of Zhoushan.