Abstract:The essay analysed 18 kinds of proteinic amino-acid in as many as 42 Chinese coniferous and broad-leavel trees. It discusses and compares their amlno-acid content and their potentical amino-acid composition in different families, categories and species and under different surroundings and in different growing seasons.In order to make a further research on their value and utility, the essay mainly studies the difference in the composition of proteinic aminoacid between grains and trees.The research shows that the amino-acid content in broad-leavel trees is abotu 2 or 3 times as much as that in coniferous. trees Thus it is more beneficial to use broad-leavel trees. But the potentical amino-acid composition in all these trees is quite similar. Trees with a relatively higher aminoacid content are aspartic acid, glutamic acid, leucine, valine, lysine, alanine, phenylalanine, arginine and so on, Those trees with a relatively lower amino-acid content include cystine, methionine, histidine, tryptophan and ammonia.The total amino-acid content in the foliage is about 3 or 4 times higher than that in grains and the potentical amino-acid composition in the foliage is totally different from that in grains and meat, especially for the 8 non-synthetic necessitions amino-acids (such as threonine, valine, isoleucine, leucine and phenylalanine) in human bodies and animals, the amino-acid content is 3 times as much as that in kaoliang and corn and twice as much as that in wheat bran. Compared with meat, the difference is even more obvious. The total percentage of leucine and phenylalanine in proteinic amino-acid is 3 or 4 times higher than that in meat.The result shows that foliage can be used as a substance for supplementing different kinds of proteinic amino-acid, so it is useful for proteinic synthesis in animal bodies. It is concluded that foliage can be used as a very good feed additve for domestic animals and fowls.