[Objective] The effects of Pinus armandii plantation canopy of different age on the dynamic characteristics of natural rainfall at Mount Mopan, Central Yunnan Province were explored in order to provide certain theoretical references for regional water and soil resource protection and forest structure adjustment. [Methods] 74 natural rainfall observations were obtained for Mount Mopan in Xinping County, Yuxi City, Yunnan Province from May to October 2019. These data included simultaneously observed rainfall and raindrops inside and outside of a middle-aged forest (15-year-old), a mature forest (40-year-old), and an over-mature forest (60-year-old) of a P. armandii plantation using the filter paper splash procedure. 11 representative rainfall events from among the data were selected, and the three forest stands for different rainfall conditions that impact the energy characteristics of raindrops were analyzed. [Results] ① The P. armandii forest had the effect of collecting and dispersing raindrops, and the middle-aged forest had the strongest effect on raindrop dispersion, followed by mature forest. The over-mature forest had the strongest collecting effect. ② The terminal speed of raindrops inside and outside the forest had a very significant positive correlation with the diameter of raindrops (p<0.01). The terminal speed of raindrops in the forest followed the order of middle-aged forest > mature forest > over-mature forest. ③ Increased raindrop diameter and rainfall intensity enhanced rainfall energy inside and outside the forest, and raindrop energy had a very significant positive correlation with both (p<0.01). Under different rainfall conditions, the rainfall kinetic energy and raindrop diameter can be fitted to a power function relationship. Raindrop energy in the forest followed the order of middle-aged forest < mature forest < over-mature forest. The weakening effect of middle-aged forest on raindrop energy was more obvious. ④ The buffering potential energy of middle-aged forest on raindrops was the best at 66.67%, accounting for 52% of the total rainfall potential, followed by mature forests at 31.58%, and over-mature forests at only 20.64%. [Conclusion] The influence of a forest canopy in reducing raindrop energy weakens as trees age. Therefore, for P. armandii plantations older than mature forests, timely harvesting and regeneration of forests should be carried out, and more attention should be given to the protection of understory litter to reduce soil erosion caused by raindrops under the forest canopy.