Forward osmosis (FO) is an emerging technology that has attracted numerous attention for its potential applications in many areas

such as desalination

waste water treatment

agriculture

and power generation.FO has shown many advantages over reverse osmosis process in terms of low energy consumption

high rejection of a wide range of contaminants and lower fouling tendency.In this paper the concept and mechanism of FO are presented

and the calculation and determination of the osmotic pressure of solution are discussed.The relationship between concentration polarization and mass transport through the FO membrane on the phenomenological model is analyzed.Some strategies about the enhancement of mass transfer processes of FO operation are suggested.The opportunities and challenges exist side by side in the development of FO technology.