The mangrove swamp, a woody plant community, grows in the coastal marsh and tidal zone in the tropical and subtropical zones. The general definition of the community means that mangrove swamps are composed of the landholding things which grow in the tropical and subtropical tidal zones. The strict definition refers that mangrove swamps are composed of arbors or shrubs which grow between the flood mark and average flood mark in the tropical coast. This research aims at studying the composition and distribution of mangroves in Kaohsiung and Pingdong County. The multiple-plot method was used in the study. There are 28 plots sampled. Based on the environmental situation, the samples consisted 10 to 177 small plots which are 1x1 square meter in size. In each plot, the trees which have DBH over 1 centimeter are all measured. Their heights are estimated and recorded. Estimation of tree number in each area, density, and average DBH was made. Five species of mangrove trees are found. They are¡G Kandelia obovata Sheue, Liu¡®Yong, Rhizophora stylosa Griff ( Rhizophoraceae ), Avicennia marina (Forsk .) Vierh ( Verbenaceae ), Lumnitzera racemosa Willd ( Combretaceae ) and Excoecaria agallocha L ( Euphorbiaceae). Bruguiera gymnorhiza and Ceriops tagal in the early research have been disappeared. There are 125 woody and herbaceous species in the mangroves which belong to 36 families and 100 genera. The mangroves mainly grow in the conservation area in the river mouths of Kaohsiung and Pingdong Country. The remaining mangroves are scattered in the areas. The mangroves were previously flourished in Kaohsiung Harbor in the south of Taiwan, but, now,there are only 12 individuals of Avicennia marina and a single tree of Lumnitzera racemosa growing in the east of Qijin. The mangroves comprise mainly Avicennia marina. The southernmost distributional area of the species is Xinlong Village in Fanglian. A few individuals of Rhizophora stylosa grow near the mouth of the Houchin stream . Many individuals of Excoecaria agallocha are found near Dapengwan of Pingdong and some of them form pure stands along streams near coastal area. The curve of diameter and structural analyses of Avicennia stands is bell shape, which is possibly the results of human affection. Because of the development in the coast in past decades, mangroves have become decreased, and will be probably disappeared in the future, if they are not protected intensively.