The invention relates to a method capable of observing the three-dimensional ditch and slop micro topographical feature in real time, which belongs to the field of topographic form measurement. The invention is characterized in that the method comprises the following steps: emitting laser positioning rays and laser positioning point spots to a measured ditch and slop surface by a topographic formpositioning device, wherein the laser positioning rays track the topographic form change in real time and positions the topographic form space positions, and the laser positioning points are used as control points of dimension determination and deformation correction on the topographical feature video sectional drawing; using an image data collection device for collecting the space coordinate information of point groups of the ditch and slop surface in real time; intercepting the topographical feature images before and after the time of the ditch and slop topographic form change, forming digital models before and after the time of the ditch and slop topographic form change after the processing by computer software, and finally realizing the non-contact type quantitative observation on anytime of the three-dimensional ditch and slop micro topographical feature. The invention is applicable to the quantitative study on the ditch and slop micro topographical feature change process, and is particularly applicable to the quantitative study on the ditch and slop gravity etching process.