Abstract: [Objective] To investigate the effect of heat shock protein （Hsp） on survival ability of Brucella under acid stress, and to assess the expression of BME E0042 gene, one of the Hsp coding genes, in the acid-treated Brucella. [Methods] The total RNA of Brucella 16M strains with or without acid treatment was extracted and was subsequently transcribed into cDNA; the relative expression of BME U0042 gene was determined by using real-time quantitative PCR （RT-qPCR）. [Results] The relative expression of BME H0042 gene in acid-treated Brucella was 6.20 fold that of the 16S rDNA, indicating the up-regulation of this gene. [Conclusion] The expression of BME R 0042 gene of Brucella is up-regulated under acid stress. Our study provides a basis for further investigation on the roles of Hsp playing in acid regulation network of Brucella.