Carbonaceous spheres with high yield and narrow size distribution were prepared by hydrothermal carbonization process using sucrose as carbon source, sodium polyacrylate (PAANa), polyvinyl pyridine (PVP) and polyethylene maleic anhydride (ISOBAM) as dispersants. The effects of type and content of these dispersants on the preparation of carbonaceous spheres were investigated. The results showed that, for the sample without using any dispersants, the yield of carbonaceous spheres increased with sucrose concentration increasing, nevertheless, clearly aggregation was also observed in the samples. Using 0.5 wt% and 1.5 wt% sodium polyacrylate (PAANa) as dispersants, carbonaceous spheres with average diameters of 1.6 μm and 0.23 μm can be respectively prepared at the sucrose concentrations of 0.7 mol/L. Polyvinyl pyridine (PVP) and polyethylene maleic anhydride (ISOBAM) can’t play effective roles for the preparation of carbonaceous spheres with small size and narrow size distribution by this method.