Abstract: Based on the numerical method for the contact of wheel and rail with a water medium, a numerical method of analyzing the adhesive force between high speed wheel and rail with a water medium is developed under the condition of neglecting the part of traction forces transferred by the water medium. For the case that there is a water medium between wheel and rail, the sharp decrease characteristic of the adhesive force between wheel and rail with the increase of the train speed is presented. The mechanism of the decrease characteristic of the adhesive force is qualitatively discussed.