Abstract: A review was made on concepts of agroforestry, principles and findings in selection of plant species component and their arrangements in agroforestry systems, and functions and practical effects of agroforestry in providing a variety of agricultural products, energy, fodder, and mulching materials,improving ecological environment and soil fertility conservation of soil and water,enhancing economic efficiency in developping countries. A list of 57 species in 29 genera which were considered to have multiple functions and often used in research or successfully applied to actual agroforestry systems was given in the paper. The author suggested that it is necessary in China to make more investigations and deep researches on potential plant components and diversified agroforestry systems and on ecological functions of each component and the system as a whole, and to do multidis-ciplinary cooperative research.