A model test was carried out to study the macro-micro mechanism of the debris flow prevention by using “anchor-slope protection”. The experiment result indicates that the exudation amount of rain water leads to pore water pressure increase, retrogressive toe sliding is not found during the experiment, and the experimental slope has infiltration softening and small-scale peristalsis. The micro-analysis indicates that the water-soil movement in slope has two forms, “water seepage among particles” and “fine particle float in water”, and the fine particles drop down with seepage water and float among grain skeleton with flowing water. As last, the fine particles were accumulated at the base of slope at the work of “anchor-slope protection”. Macro-micro experimental analysis indicates that particle micro-movement changes the structure of the slope as the relative stable structure of “fine particle drop to the bottom and compaction, the upper coarse particle skeleton is stable” is formed, and this stable structure reduces the incidence of debris flow.