Abstract: The adhesion force of soil to solid materials includs molecular attraction, water-ring attraction and stickiness-stagnancy force of water-film. The molecular attraction of soil adhesion was derived from Lifishitz' s molecular interaction theory between two macrobodies. The water-ring attraction of soil adhesion was obtained based on the energy of soil adhesion system, which can effectively reveal the soil adhesion rules about the contact angles for water on solid material surfaces being from 0 to 180 degrees. The relation between the stickiness-stagnancy force of water-film and the thickness of water-film was analyzed.