Abstract: The analysis on the composition and physical characteristics of Liaohe extra- viscous crude oil is made.The results show that the high gum content makes this kind of oil difficult to flow. It is considered that the best way to transport this oil is to develop an oil- soluble viscosity reducing agent to restructure the gum and reduce viscosity efficiently at higher temperature. The trial test on the influence of composition and distribution of molecu- lar weight of viscosity reducing agent on viscosity reducing behavior is made.