Abstract: Three species of nanmu, the evergreen broad-leaved trees, are distributed in Ji-angsu Province. They are Phoebe sheareri growing in subtropic zone, Machilus leptophyllus growing merely in central subtropic zone and Machilus thunbergii growing in central subtropic and warm temperate zones. The northern boundaries of the three nanmus are situated at Baohua Shan in Jurong County and Longchi Shan in Yixing County, Jiangsu Province and Lao Shan, Shandong Province respectively.Geographic distributions and ecological environments of these three nanmus in Jiangsu are described in detail. A mixed forest, of deciduous and evergreen broad-leaved trees is usually dominated by Phoebe sheareri and some species of deciduous trees; An evergreen broad-leaved forest is often composed of Machilus thunbergii and many other species of evergreen broad-leaved tress.Characteristics of the composition and structure of the above mentiond 2 mixed nanmu forests are thoroughly studied. These 2 nanmu forests contain some rare species and species of superior timber quality though they exist in a very limited area and on the verge of extinction.Proposals for the preservation of the precious timber resources are intensively discussed.