With the rapid advance of urbanization in China, the lack of fresh water resources has become a big problem for the national economic and social development. Especially in sea island cities, the development and utilization of nonconventional water resources is imperative. Taking the island city of Zhoushan as an example, based on the field investigation of development and utilization of non-conventional water resources, the management experience of developing and utilizing the reclaimed water and seawater in Zhoushan City is analyzed. The effective ways of developing and utilizing nonconventional water resources are summarized, and the relevant problems are put forward. Some measures and suggestions for further strengthening of development and utilization of non-conventional water resources are proposed from the following aspects: planning and management, legal standards, financing channels, preferential policies, technical development and demonstration, market-oriented operation mechanism and propaganda.