This paper is the third year's study of "The geomorphological study of coast sand dunes of Taiwan". The study areas include the eastern and southernmost coasts of Taiwan. Based on airphoto interpretation, particle size analysis, field studies etc., the results are summarized as follow: 1.In Southern Taiwan, most of the streams are short, and supply only a little sand. The eastern coast of Taiwan is fault coastline, so there are any cliffs along the coast. The extension of sand dunes is not so wide as that in the western and the northern Taiwan. 2.In southern coastal area, most of sand dunes are distributed on the plain near river mouths and on the coral reef platforms, such as Hai-kou, Chiu-peng, and Fou-chiu-sa, ets. Various types of dunefields: dome dunes, barchans, sandfalls, and pseudo dunes were easily observed there. The supply of sand come from the shelly fragments and mineral grains by coastal erosion and suspended sediment. The sizes of the gray and white color particles in the southern coast are smaller than those in the eastern coast. 3.The sand dunes n the eastern faulted coast are distributed only on the plain near river mouths like Pei-pu and Chih-pen. Most of the sand supplies come from suspended sediment. The sizes of the particles with gray and black color are bigger than those in the southern coast. The features of dunefields are simple only gradual undulation along shoreline. 4.Because of the dunefield was used as fishery, watermelon planting and cemetery, most of the sand dunes were leveled off entirely. Some of the residual sand dunes were stabilized by windbreak forest. For sand dunes showing a function of protecting coasts, they had better be well-planned and well-used so as to maintain the sustainable utilization of land sources.