During the production and processing of polypropylene, the fine dust generated is prone to combustion and explosion accidents. Targeting two typical ignition sources, electrical sparks and high-temperature surface objects, the study investigated the combustion sensitivity of suspended and accumulated polypropylene dust using a minimum ignition energy test apparatus for dust clouds, an electrostatic spark sensitivity tester, and a minimum ignition temperature test apparatus for dust clouds/layers. The results indicate that the minimum ignition energy of 10~13, 18~23, 25~38 μm polypropylene dust clouds is significantly lower than that of 48~75 μm dust clouds. The minimum ignition energy of polypropylene dust clouds shows a trend of first decreasing then increasing with the rise of dust concentration, powder injection pressure, and ignition delay time. In accumulated state, the minimum ignition energy gradually increases with particle size, indicating reduced electrostatic spark sensitivity. Under single-variable conditions, the minimum ignition temperature of polypropylene dust clouds displays inflection points with increasing particle size due to dust agglomeration phenomena.