Abstract: The rheological behavior of coal-oil slurry (COS) and coal-liquefied residue is fundamental information for direct coal liquefaction. The development and corresponding models of the rheological properties of Chinese COS under conditions，such as at ambient temperature under atmospheric pressure，during heating under normal pressure and at elevating temperature under high pressure，were summarized. The predominant factors affecting the viscosity of COS systems，such as the nature of solvent，the swelling property of coal，and the thermal dissolution or initial liquefied products were introduced. It could provide guidance for the research on rheology of COS and liquefaction residue.