Abstract: The effects of imidization method，coagulation bath and temperature were studied on the structure and separation performance of polyimide membrane，prepared by using pyromellitic dianhidride and 4,4′-oxydianiline as raw materials. The optimal synthesis conditions of polyimide membranes were as follows：15%(wt) polyamide casting solution，the coagulation bath was 30 %(wt) ethanol aqueous solution, chemical imidization at room temperature for 48 h. The synthesized polyimide membrane showed good nanofiltration performance for organic mixtures of lubricant oil with acetone and benzene solvents. The rejection rate was 66% and the flux was 4.26 L/(m2·h).under the steady-state operation with an operation pressure of 2 MPa. These results are important to developing commercial nanofiltration membrane for organic solvent mixtures.