Abstract: Based on the unsaturated soil solute transport equation-the Convection Dispersion Equation, and its analytical solution and lab experiment, the characteristics of soil solute transport was studied under sprinkler irrigation and flood irrigation. The result showed that the main concentration of K⁺ was distributed within 20 cm of soil surface with flood and sprinkler irrigation because of the soil adsorption. Under flood irrigation, the pore water velocity was great,NO₃^- transported quickly, the dispersion strong and NO₃^- concentration mainly distributed out of root zone after irrigation, which was not convenient for crop uptake and eased to pollute under grounder water. Under sprinkler irrigation, the intensity of water supply was low, the pore water velocity small, the dispersion weak and NO₃^- transport slowly, which leaded to NO₃^- distribution within surface soil and convenient for crop root uptake. It is the key reason why sprinkler irrigation saves water and keep on fertilizer.