Cold flow properties of Iranian crude oil have been investigated by two different imidazolium ionic liquids including 1-dodecyl-3-methylimidazolium reduce the pour point up to bis(trifluoromethanesulfonyl) imide ([C(12)min](NTf2]) and 1-tetradecyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide ([C(14)min](NTf2]). ([C(14)min](NTf2]) showed high ability to 12 degrees C optimal performance by addition of 2000 ppm. Wax crystallization behaviour of untreated and treated crude oil was monitored using differential scanning calorimetry (DSC) and the polarized optical microscopy (POM). Results from DSC and POM revealed that the presence of both ILs changes the process of crystallization and extends wax precipitation time. Furthermore, rheological behaviour of the crude oil was improved and viscosity was decreased by 73% at 23.5 degrees C and 87% at 15 degrees C by addition of [C(14)mim][NTf2].