Abstract: The sieved samples of petroleum coke and coal with narrow particle size distribution were employed to assess the effect of particle size on packing characteristics and flowability by measuring the compressibility,angle of repose,shear characteristics and flow energy.Meanwhile,the difference of these two powders was analyzed.Bulk density and basic flow energy increased with the enhancement of particle size.Angle of repose,compressibility,specific energy and cohesion of the powder decreased while the flowability was improved with the increase of particle size.The cohesion of the two powders increased while the flowability decreased as the increase of consolidation level.The shear characteristics showed no significant difference under the same consolidation level.The packing characteristic and flowability of fine particles (<70 μm) were more sensitive to the consolidation stress compared to coarse particles.The bulk density of petroleum coke was higher than that of coal at the same condition.The petroleum coke showed similar flowability to coal when their size was larger than 70 μm,while the former was slightly lower when their size was smaller than 70 μm.