The treatment of shale oil & gas produced water is a complicated process since it contains various organic compounds and inorganic impurities. Traditional membrane processes such as reverse osmosis and nanofiltration are challenged when produced water has high salinity. Forward osmosis (FO) and membrane distillation as two emerging membrane technologies are promising for produced water treatment. This chapter will focus on reviewing FO membranes, draw solute, and hybrid processes with other membrane filtration applied to produced water treatment. The barriers to the FO processes caused by membrane fouling and reverse draw solute flux are discussed fully by comparing some FO fabrication technologies, membrane performances, and draw solute selections. The future of the FO processes for produced water treatment is by summarizing life cycle assessment and economic analyses for produced water treatment in the last decade.