The dispersion coefficients of electrolyte solute in flow of different slope and sediment concentration are calculated using the mathematical model of electrolyte pulse transferring in laminar flow. The dispersion coefficient is liner related to the velocity of flow when the sediment concentration is relatively low; The sediment concentration is high, it affects intensively the dispersion coefficient, and make their liner relationship bad. These results shows that the relation between dispersion coefficient and sediment concentration and velocity deserves to more discuss.