The utility model discloses a demonstration instrument of destroying the soil actively and negatively. A movable baffle which is vertical with the bottom surface of a perspex box is arranged in the perspex box, and a dynamic screw thread which stretches out of the perspex box and is connected with an operational handwheel screw thread connection is arranged on a lateral face of the movable baffle. A plurality of soils which will be demoed and a colored thin layer of sand are scattered in the form of layer in the perspex box by a hopper above the middle of the perspex box. When the operational handwheel is wheeled in clockwise or anticlockwise, the active soil press or negative soil press against the baffle is generated. As the development of the active soil press or negative soil press, the soil reaches the limited state, then, parts of the soil and the colored thin layer of sand are slipped or bulged, so a sliding face is formed and an active or negative destruction of soil is generated. At that time, the included angle between the sliding destruction face and the horizon can be measured by a protractor. Besides, the phenomenon of deformation and destruction of each soil in the state of being active soil press or negative soil press can be observed by wheeling the operational handwheel.