Abstract: For the poor fluidity of coal tar generated from circulating fluidized bed polygeneration system, a series of research was carried out to decrease the viscosity. Through the analysis of X-ray diffraction, the possibility that the wax crystal increases the viscosity at room temperature was excluded. The viscosity and contents between coal tar and coal tar pitch were compared, and the impact of quinoline insoluble on the softening point was also investigated. The results reveal that it is reasonable to employ the distillates to decrease the viscosity of coal tar. Four kinds of distillates were blended in the coal tar to improve the fluidity, and the composition of the distillates was gotten through the GC-MS analysis. It is concluded that the molecule which contains both hydrophilic groups and hydrophobic groups possesses a great effect on the viscosity reduction, and the more the amount, the better the viscosity reduction. Four kinds of mono-component additives were tested, and the theory was verified. For the viscosity reduction, the molecule with both groups is better than that with only hydrophobic groups.