Preparation method of composite forward osmosis membrane

The invention relates to a preparation method of a composite forward osmosis membrane. At present, a phenomenon of inner concentration polarization exists in a forward osmosis process. The method disclosed by the invention comprises the following steps of: firstly, adding polysulfone and an additive into a solvent to be agitated and dissolved to obtain a polysulfone membrane casting solution which is uniformly dispersed; preparing a cyclodextrin aqueous solution with mass percent of 0.05-5% and a mellitic acyl chloride n-hexane solution; scraping the polysulfone membrane casting solution which is uniformly dispersed on non-woven fabric by using a scraper; immersing into de-ionized water of a coagulating bath to obtain a polysulfone ultra-filtering bottom membrane; and immersing the polysulfone ultra-filtering bottom membrane into the cyclodextrin aqueous solution and the mellitic acyl chloride n-hexane solution in sequence and curing to obtain the composite forward osmosis membrane. The method is simple in pr