Our L-Tryptophan is an important precusor substance of auxin biosynthesis in plant. L-Tryptophan powder 98.5% has the similar structure of IAA. It widely exists in higher plant. There are two ways to synthetic auxin. The first is tryptophan oxidizes and deaminize and form indole acetone,then decarboxylation and form IAAId; Under the corresponding enzymes IAAId oxsidizes indoleacetic acid. The second way is decarboxylation and form to tryptamine then tryptamine oxsidize deamination finally forms tryptophan.