Abstract: Seawater desalination is one of the important ways to solve the problem of island water shortage. To promote the application of water desalination on islands, we systematically analyzed the environment of seawater desalination industry development through PEST model with data collection and field investigation, which consists of four aspects political policy (P), economy (E), social culture (S) and technology (T). With the overall analysis of their strengths, weaknesses, opportunities and challenges through SWOT-PEST matrix, we discussed the development situation and prospect of seawater desalination industry on islands, and then put forward the strategic countermeasures and safeguard measures from the aspects of national policy, market economy, public acceptance and technology innovation,which is considered as the theoretical foundation for the industry development of seawater desalination on islands.

Key words: island, seawater desalination, industry environment, PEST model, SWOT-PEST matrix analysis, strategic countermeasures