Based on the PM_2.5 and PM₁₀ mass concentration data obtained from 51 national air quality monitoring stations and the corresponding rainfall intensity data in automatic meteorological stations in Hubei Province from 1 January 2015 to 31 December 2017, the impact of rainfall intensity on PM mass concentrations under relatively different humidity conditions was analyzed. The results showed that light rain occurred most frequently in the pollution process, with Xiangyang being affected for up to 587 h. PM concentration would not change drastically under the effect of precipitation. Mean rainfall intensity responsible for wet growth of PM₁₀ and PM_2.5 was mainly 1.4 mm/h) than that of PM₁₀ (>1.0 mm/h). Precipitation was more likely to produce a wet removal effect for a greater initial value of PM mass concentration, and on the contrary, a wet growth effect was more likely, with the threshold of PM₁₀ mass concentration being 150 μg/m³ and that of PM_2.5 mass concentration being 95 μg/m³. Wet removal played a leading role in lower humidity (∼60%) and greater rainfall intensity, but wet growth played a leading role in higher humidity (∼90%) and lower rainfall intensity. As the precipitation level increased (rainfall ≥1.5 mm·h⁻¹), the wet removal to PM₁₀ mass concentration was enhanced more obviously. The variations of PM_2.5 had similar distributions to those of PM₁₀ under the effect of precipitation, but the wet removal effect of precipitation was weakened and the wet growth effect was enhanced.