A　thermally　induced　phase　separation　followed　by　non-solvent　induced　phase　separation　(TIPS-co-NIPS)　was　used　to　prepare　polyethersulfone　(PES)　substrate　with　reduced　internal　concentration　polarization　(ICP)　for　thin　film　composite　forward　osmosis　(TFC-FO)　membrane.　Using　polyethylene　glycol　(PEG)　as　the　additive,　impacts　of　TIPS　process　on　substrate　properties,　TFC　layers　and　FO　performances　were　investigated.　The　results　revealed　that　the　substrate　prepared　by　TIPS-co-NIPS　method　with　10　s　cooling　time　showed　a　fully　finger-like　structure,　enhanced　permeation　performance　and　better　surface　hydrophilicity.　As　a　result,　the　corresponding　TFC-FO　membrane　exhibited　44%　lower　structural　parameter　than　the　TFCFO　membrane　based　on　NIPS　substrate　(684　pm　versus　380　mu　m),　high　water　fluxes　up　to　32.9/20.4　LMH　and　reverse　salt　fluxes　of　14.1/8.2　gMH　in　the　PRO/FO　mode　using　1M　NaCl　as　the　draw　against　DI-water　feed.　Therefore,　the　proposed　TIPS-co-NIPS　method　utilizing　PEG　as　the　additive　may　be　considered　as　a　feasible　approach　to　regulate　substrate　structure　and　property　for　TFC-FO　membrane.　(C)　2017　Taiwan　Institute　of　Chemical　Engineers.　Published　by　Elsevier　B.V.　All　rights　reserved.