Abstract: Rotation is an economical and efficient measure to control crop soil-borne diseases. To further understand its mechanism， in this study， the phospholipid fatty acid （PLFA） profiles of soils from different cropping fields were analyzed by employing PLFA profiling technique. The results showed that in soils from rice-cotton and rice-maize rotation fields， the content of total PLFAs was higher than that from rice-rice continuous cropping fields， which was lower than that of uncontinuous cropping. Results of soil microbial community structure analysis indicated that bacteria were predominant， followed by fungi and actinomycetes， in soils from all fields. However， content of each type of microbes， especially bacteria， was higher in soils from rotation cropping fields than that in continuous cropping fields. Collectively， these results revealed that both amount and composition of microbial community varied in soils from different cropping fields， and rice\|upland crop rotation increased the microbial amount and significantly altered the microbial composition.

Key words: crop rotation, soil microbe, microbial community structure, phospholipid fatty acid （PLFA） profiling