To investigate molecular mechanism of traditional Chinese medicine Rheum offcinale against Yersinia pestis, whole genome DNA microarray that contains 4005 annotated genes of Y. pestis was used. The minimal inhibition concentration (MIC) of R. offcinale extract against Y. pestis was determined by liquid dilution method. The gene expression profile of Y. pestis was performed after exposured to R. offcinale extract at a concentration of 10 X MIC for 30 and 60 minutes. The total RNA extracted and purified from Y. pestis were reverse-transcribed to cDNA and labeled by Cy3-Cy5 dye. The labeled probes were hybridized to the microarray and the results were obtained by a laser scanner and analyzed by the SAM software. The microarray data was confirmed by RT-PCR. The platform of the DNA microarray-based bacteria transcriptional profiling was eshtablished. The results revealed general gene expression changes of Y. pestis were a global phenomenon. Down-regulation of genes encoding proteins involved in ribosome protein synthesis was a remarkable change. Genes encoding cell envelope and transport/binding proteins were the major changed genes of the Y. pestis in response to R. offcinale.