Abstract: In order to assay the effect of heat shock ( HS) on the stress tolerance of the probiotic bacterium, Lactobacillus reuteri serves as the research objective in this study. The survival and gene expression of L. reuteri under stress condition has been determined via CFU counting method and q PCR analysis. The results showed that the HS pretreatment ( 40 ℃, 30 min) significantly ( p < 0.05) increased the survival of L.reuteri under the subsequent heat stress ( 45, 48, 51 ℃) , salt stress ( 0.1%, 0.3%, 0.7%, m/v) and oxidative stress ( 0.3, 0.6, 1.2 mmol/L) , respectively. In addition, the HS pretreatment ( 40 ℃, 30 min) markedly enhanced the transcriptional expression of thiol peroxidase and peroxiredoxin.It suggested that HS pretreatment could improve stress tolerance via increasing the expression of anti-stress genes.These results provide a theoretical basis for the large-scale application of probiotics.