Abstract: In order to solve the plant source pollution caused by airborne pollen in urban greening construction, the temporal and spatial variation of airborne allergenic pollen transmission and its influence on the concentration of airborne particulate matter in the forest were studied, which provided the basis for preventing and controlling urban airborne sensitized pollen pollution. A typical airborne allergenic pollen plant, Neem, which is frequently used in urban greening in Chengdu, was taken as the research object, and the daily variation and horizontal spatial spread of airborne allergenic pollen were studied by selecting the blooming period of Neem. The result showed that: (1) There was a single peak curve in the daily variation of the pollen concentration of neem, that is, the pollen concentration increased continuously from 6:00 to 14:00, and reached a peak at 14:00. From 14:00 to 20:00, it continued to decline. The concentration of pollen drifting from 12:00 to 15:00 was significantly higher than that of other periods. In the horizontal direction, the pollen concentration in the downwind direction was higher than that in the upwind direction. In the downwind direction, the pollen concentration showed a single peak curve, which increased with distance and reached a peak at 20 m. The drifting concentration of pollen in the upwind direction showed a bimodal curve, and the peaks appeared at 9 m and 20 m. Due to the influence of Neem pollen dispersal, the horizontal distribution trend of airborne particulate matter concentration in the C. camphor forest was roughly the same as that of pollen concentration, and it also showed that the downwind direction was higher than the upwind direction. At the horizontal distance, the influence of neem pollen on airborne particles was mainly in the range of 0-30 m.