The paper reported antimicrobial function of different trees species in woodland along the Grand Canal, Yangzhou, China, at 16:30-17:00, Sep 5, 2004. The tested result showed that in different communities of Platycladus orientalis,Osmanthus fragrans, Cedrus deodara, Albizzia julibrissin, Cinnamomum camphora had antibacterial action. The content of pollutant bacteria in the forest atmosphere (1.5~1.8 m above the land) decreased obviously,which amounted to 23.59%~99.78% compared with the control in open area and 10.08%~99.71% compared with the near communities away from {15 m} distance. There was nat antifungal (against mold) effect in general; only two tree communities for Osmanthus fragrans (decreased 40.66% compared with the near 15 m distance) and P.orientalis (decreased 24.73% than in open area) had less antifungal effect. At the same time, the antimicrobial activities were tested by the extractive volatile of foliage for more tree species in lab. The results showed that antibacterial activities to against Staphalococus aureus and Escherichia coli were the highest in P.orientalis , Manglietia yuyuanensis and C.camphora , and higher in Koelreuteria bipinnata, Viburnum macrocephalum, Metasequoia glyptostroboides, Eriobotrya japonica, Ginkgo biloba, C.deodara, Magnolia grandiflora, Sabina chinensis. Most of the tree species tested had less antifungal activities against Fusarium graminerum and Glomerella cingulata. While Ginkgo biloba, Cinnamomum camphora, S.chinensis, Elaeocarpus sylvestris and C.deodara had higher antifungal activities against G.cingulata than others. The P.orientalis, C.camphora, S.chinensis Magnolia grandiflor, G.biloba, Acer mono, Acer palmatum had higher antifungal activities against F.graminerum than others.The research results recognized that the suitable cultivated tree species in cities were P.orientalis, C.deodara, C.camphora and M.glyptostroboides.