Abstract: In order to prepare high concentration, low viscosity and high stability of coal water slurry, dodecyl benzene sulfonic acid starch ester was synthesised w ith starch as raw material, sodium dodecyI benzene sulfonate as esterification agent, oxidized dodecyl benzene sulfonic acid starch ester was prepared by oxidation pro cess with potassium permanganate as oxidant. The structure of the dispersant was characterized by Fourier Transform Infrared Spectroscopy, and the apparent viscosit y, rheology and static stability of the coal water slurry were measured. The results showed that the dispersant had good dispersion to coal water slurry. When the disper sant dosage was 0.5% and the concentration of coal water slurry was up to 69%, the coal water slurry had good dispersion and stability. The apparent viscosity was 1 1 87 m Pa:s, and the water content was 5.61%.