The effects of neokstose on the growth of Escherichia coli and Bifidobacterium in vitro were investigated. The results showed that the growth of Escherichia coli utilizing neokestose in vitro is weaker compared with fructooligosaccharide(FOS) and glucose,but the differences are not significant(p>0.05). However,the proliferation rate of Bifidobacteria in the medium with neokestose is very high,which is 1.4 times and 2 times as much as that in the media with FOS and glucose,respectively.