Soil available nutrients, soil enzyme activity, soil microbial diversity and cucumber yield in a field under crop rotations of cucumber with wheat and hairy vetch with conventional methods and PCR-DGGE to study effect of the rotation on soil micro-ecological environment and yield of cucumber. Results indicate that the rotations significantly increased cucumber yield and effectively improved the soil micro-ecological environment. The rotation of wheat-cucumber increased the yield of cucumber the most significantly (p<0.01), by 28.04%, and improved the overall activity of polyphenol oxidase, catalase and urease. The rotation of hairy vetch-cucumber increased the yield of cucumber by 16.78% and improved the content of soil available nutrients, and the invertase activity significantly over CK (p<0.01) DGGE analysis shows that the rotation helped increase the diversity of bacterial species in the rhizosphere, while decreasing that of fungi at the late fruit-bearing stage. The effect of the rotation of hairy vetch-cucumber was more significant. The rotation of wheat-cucumber showed certain effect on rhizospheric soil fungi as well as the bacterial community structure 30 days after transplanting of cucumber. To sum up, the rotations of cucumber with wheat and with hairy vetch help mitigate the hazard of consecutive cropping of cucumber, improve the soil microbial eco-environment and raise the yield of cucumber.