Abstract: In this review, in nine plants the interrelations of phytoecdysones on their chemical structure and their biosynthetic pathway have been discussed. We propose the general character of C27, C28, C29 phytoecdysones in their biosynthetic processes, which based on the biogenesis of C27 phytoecdysones was expounded, and consider the common biogenetic precursor existed, and suggest the biosynthetic mechanism of some special phytoecdysones, and predict some special new phytoecdysones (Fig. 9 ) possibly existed in the special plant.

Key words: Ecdysone