The depth estimation methods can be divided into two categories, active vision and passive vision. The five different passive vision range finding methods are introduced, including stereo vision, structure from motion, shape from shading, depth from focus and depth from defocus, and their imaging principles, mathematical models and measurement methods are also analyzed. Finally, the depth estimation methods based on computer vision are summarized, and the limitation of the current measurement methods is analyzed. The further direction of improvement algorithm is using the different modules in the computer vision system. The association depends on combining the different weighting factors in the actual environment with passive depth estimation methods. This is a hot point in the present computer vision.