Abstract: To gain insight into the nature of disease incidences and microbial community shift, the dynamics of soil microbe population induced by continuous cucumber cropping was studied based on PCR-DGGE approach. Results revealed that continuous mono-cropping caused great bacterial species shift, of which Bacteriovorax sp.(indentity of 93%), Pseudomonas sp. (indentity of 97%) and two uncultured bacterial reduced in population, while Sphingomonas sp. (100% similarity) and another uncultured bacterium increased. Monocropping has little effect on eukaryote in soil. For all samples analyzed using culture-independent approach, the bacteria and eukaryotic species shift was more sensitive in rhizosphere than in bulk soils. In the whole growth cycle, the variation of rhizosphere bacterial number was closed coincident with cucumber developmental stages, indicating vigorous root growth and/or root exudates were the potential factors that determined soil bacterial population.