Abstract: With the rapid propagation system of germchit intelligent monitor and control,the differences of Syzygium samarangense cutting with mother plant leaves were compared in photosynthesis characteristics during their rooting period.The results showed that the net photosynthetic rate(Pn)of cutting leaves was higher than that of mother plant leaf at cuttage prometaphase,while the effective quantum yield of photosystemⅡ(Yield)was maintained at high level all time in vitro.After rooting,the electron transfer rate(ETR)of cutting leaves of Syzygium samarangense was higher than that of mother plant leaves.The results indicated that,by the rapid propagation system of germchit intelligent monitor and control,the photosynthetic ability of Syzygium samarangense cutting leaves were not inferior to that of mother plant leaves,which maintained the level while cutting off.The rooting of cuttings depended on leaf photosynthesis for furnishing matter and energy.