Abstract: Abstract：Contents of endogenous hormones IAA，ZR，DHZR，GA3，ABA，reducing sugar，soluble sugar，starch and dry matter in yam（Dioscorea opposita）bulbils were tested over developmental cycle. The results showed that concentration of IAA was low and varied gently，so did that of DHZR，while ZR content was higher than DHZR content throughout bulbil developing stage and changed more sharply especially at early stage. The content of GA3，compared with other hormone contents，was very high throughout bulbil developing stage，it maintained 1 220.7 ng · g-1 at last，though it began to reduce after bulbils became brown. The content of ABA fluctuated from 730.9 ng · g-1 to 954.9 ng · g-1 before bulbils became brown completely，then increased sharply. The content of reducing sugar reduced rapidly at first and changed little after bulbil browning. The content of soluble sugar curve rose，while the contents of starch and dry matter rose linearly. When bulbils were mature，the contents of soluble sugar，starch and dry matter reached the peak. The results indicated that high GA3 and ZR content were necessary for bulbil development，and bulbils would to be mature after the ratio of GA3 to ABA was less than 1. As the result of endogenous hormone regulation，matters such as reducing sugar，soluble sugar，starch and dry matter continued to accumulate until the bulbils matured and the vines on which bulbils grown were yellow and dry.

Key words: Dioscorea opposita, bulbil, endogenous hormone, starch, soluble sugar, reducing sugar