Abstract: Technology about comprehensive modification of waxy crude oil has been successfully applied in low flow pipelines. In order to improve the effectiveness of the technology and extand its appilcable coverage, what critical is to find out a cost effective but highly efficient additive, to link closely the rheological characteristics of crude oil with petrochemistry, and to make a break through by studying the interaction between crude oil and additive. Analysed in this paper are the classification of petrochemistry, the morphology and crystallizing behavior of the wax in oil, the gum and asphaltene in oil and their effects on wax, as well as the effects of other liquid hydrocarbons in the oil upon rheological properties of the oil and upon the modification of oil flowability. It is pointed out that scientific research shall be made using multiple analytical means available, including analysis and integration, so as to make further achievements.