The crystallization of waxes at low temperatures from crude oils and products,which are composed mainly of n-alkanes, is a major problem in oil produetion and transportation[1].Pretreatment of the crude oil with Pour point depressants (PPDs) has been proved to be an effective solution to lowering the pour point and viscosity of the waxy crude oil to facilitate pipelinc transportation [2-3].Studies have been concentrated on the effect of simulation oil or crude oil with PPD [4].