Abstract: The influence of pre-treatments on apparent viscosity of blue-green algae, the maximum solids loading, rheological property and static stability of the coal-algae slurry was examined. The results show that chemical treatment, agitate and heating are useful pre-treatment methods. The apparent viscosity of bluegreen algae is declined from 72mPa·s to 21.8mPa·s (sharing rate 100s^-1). The decrease in the apparent viscosity of blue-green algae is due to the structure of blue-green algae destroyed, which is favorable for the increase in the maximum solids loading of coal-algae slurry. When the mass ratio of water and blue-green algae is 1∶1, the maximum solids loading of coal-algae slurry could reach to 60%, which meets the industry requirement. After blue-green algae is added to coal-water slurry, the sediment time of coal-algae slurry is changed from 4h to 72h. Coal-algae slurry is a pseudo-plastic liquid, which is shear-thinning and easy to transport.