We utilized a simulated rainfall approach to quantify the influence of the amount and duration of rainfall (15 mm/h and 30 mm/h) on the removal of particles of different diameters from leaf surfaces. We analyzed three aspects of the data-the process of dynamic change, dust retention threshold, and the relationship between rainfall and leaf surface dust. The results showed that the retention rate of leaf surface dust first exhibited a sharp drop and reached a steady state over time. The influence of rainfall on the leaf surface dust was the most obvious at the beginning. The duration of wash-off decreased as rainfall intensity increased. The threshold values for particle retention mass and rate decreased relative to increases in rainfall intensity. The threshold values of particle retention mass were 10-100 μm > 2.5-10 μm > 0.2-2.5 μm, which were consistent with the state before rainfall. Most three-particle size fractions on Platycladus orientalis could be washed off quite effectively. Particles of 10-100 μm on Euonymus japonicus were more likely to be washed off than the smaller particles. In addition, particles on Pinus tabuliformis were not easily washed off, with 30%-50% threshold values for retention rate. Rainfall and particle retention rate fit well and particle retention rate had decreased exponentially as rainfall intensity increased. With a 10 mm change in rainfall, there was a substantial decrease in particle retention rate, after which the decreasing curve became relatively gentle.