Pollen allergy is a very serious seasonal respiratory disease. However, there has been a lack of understanding how pollen allergens enter the body and act on cells. This study focused on the release, transport and characteristic of Pla a3 allergen of the Platanus acerifolia pollen. Pla a3 protein was purified by prokaryotic expression system for preparation of polyclonal antibody. The distribution and release of Pla a3 protein in pollen were observed by immunohistochemistry. Mice were immunized with purified Pla a3 protein and SPPs, respectively. The pathological examination of mouse lung tissue proved that SPPs, as a fine particle in the range of 0.1-1μm, can enter the deep part of the lung directly through the respiratory tract and led to inflammation. Furthermore, DAPI staining confirmed a certain amount of nucleic acids in SPPs. After incubation with SPPs for 6 h, the Pla a3 mRNA could be detected in A549 cells by PCR. This suggests that nucleic acid wrapped in SPPs could be delivered into A549 cells. These results could provide a new clue and experimental data accumulation for further study on the mechanism of pollen sensitization.