Abstract: Highly waxy crude oil produced in Sudan No.6 Block needs to be delivered to Khartoum Refinery 730 km away for processing. To ensure safe operation of long-distance pipeline and meet the substantial increase of oilfield output, the technology of viscosity reduction by cracking which can make decomposition, isomerization, aromatization, hydrogen transfer, superimposition, alkylation and other reactions of heavy oil hydrocarbon is combined with the method of mixing light oil according to crude properties and actual production, thus ensuring a high effect in the reduction of viscosity. Site application results show that viscosity reduction can significantly change flowability of highly waxy crude oil to enhance the crude oil transportation capacity of the pipeline, being worth promotion.