Abstract: Coal bio-oil slurries (CBS) with different coal concentrations were prepared by mixing different type of coal and bio-oil. The apparent viscosity, rheological properties, maximum solid concentration and static stability of the prepared CBS were examined. The result shows that CBS are non-Newtonian fluid with a certain yield stress, and the rheological behavior of CBS can be described by the Bingham plastic fluid model. Both the apparent viscosity and the yield stress of CBS increase with increasing of solid concentrations. The apparent viscosity decreases with increasing of shear rates. The solid concentration of stable CBS prepared by Yangquan anthracite can reach as high as 42% without any additives, followed by bituminous coal and lignite. The flocculation network structure formed by coal particles in the bio-oil can keep good static stability of CBS for 4.0~5.0 days without formation of soft sediment, and for months without hard sediment.