A kind of soluble polyimide(PI)was synthesized based on 4

4’-oxydiohthalic dianhydride(ODPA)and 4

4’-diamino-3

3’-dimethyldiphenylmethane(DMMDA) via low temperature solution polycondensation and chemical imidization．The structure and properties of the obtained PI were characterized by measurements of FT-IR．1H-NMR

DSC and TGA etc．The results showed that the PI was readily soluble in polar solvents such as DMF．DMAc and NMP etc．Its glass transition temperature was 264℃ and 10％thermal deeomposition temperature under N2 was 521℃．The tensile strength was 137 MPa

and the elongation at break was 18％．The asymmetry membrane was prepared by phase inversion method of ODPA—DMMDA and was observed by SEM．In the sulfur reduction experiments

the membranes display good selectivity and hish pervaporation performance for thiophene in the gasoline．The enrichment factor was 3．68 and the flux was O．92 kg／m2h when tested with a n—heptane／thioohene feed at 350 K.