An index was developed for analyzing the promising countries for seawater desalination plant and related data sets were collected and analyzed. Each indicators was standardized by scale readjustment method and Delphi method was used to calculate the weights for indicators from questionnaire survey by experts in seawater desalination plant field. Twenty three indicators were selected and they were classified into three groups, economic, social, and environmental indicator groups. Eleven countries (Saudi Arabia, UAE, Kuwait, Iran, Qatar, China, Singapore, India, Algeria, Turkey, United States) were selected considering present data availability and index for each country was calculated. The results show United States and China took the first (0.537) and second (0.490) place for the most promising country for seawater desalination plant. However it will not be easy to play a significant role in the markets because of present seawater desalination technology level and national policy, etc. Saudi Arabia took the third (0.329) place and other countries which has more than 0.2 index value can be considered as a promising countries for seawater desalination plant. We can establish a strategy to export our seawater desalination technology and plant using the result of this study. The developed index can be applied to other countries, which were not included in this study, when their data is available.