The invention belongs to the technical field of water and soil conservation study devices, and relates to a dynamic observation device used for a slope topography evolution process. The two hosts emitparallel, equal-height and overlapping laser planes from different orientations, and the laser planes are projected onto the slope topography; an image collecting device shoots the slope topography which laser rays are projected onto at an angle perpendicular to the layer planes to form a video screenshot, the video screenshot is imported into a computer to form a three-dimensional stereogram, and then parameters such as the slope volume and the slope gradient are calculated. According to the device, by rotating rotary knobs of mechanical fine tuning devices in the topographic meter hosts, equal-interval parallel accurate adjustment of laser ray planes is achieved; according to the device, by observing a fixing bolt on a support and a worm handle rotary knob in a view screen box, moving and rotation of a camera used for image collection are controlled. The invention provides a novel topographic meter through which the spacing and the angle of a linear laser can be conveniently calibrated, and all the topographies including local deep grooves on an eroded slope can be accurately observed.