Heat stress (HS) in summer will seriously affect the health and performance of dairy cows. To alleviate the injury to dairy cows caused by HS, we added the rumen-bypassed tributyrin to the feed. We determined whether cows were in a heat-stressed environment by testing the temperature humidity index in the morning, at noon, and in the evening. The detection of anal temperature and respiratory frequency further proved the HS state of the dairy cows. The quantificational real time PCR results showed that tributyrin could significantly reduce the relative expression of tumor necrosis factor α, interleukin 1β, and Interleukin 6. Western blot results showed that tributyrin could alleviate the lymphocyte inflammatory response by inhibiting the mitogen-activated protein kinase and nuclear factor-кB signaling pathways. To further detect the effect of tributyrin on HS in dairy cows, routine biochemical and blood tests were carried out. The results showed that the contents of aspartate aminotransferase, total bilirubin, creatinine, albumin, and globulin were significantly reduced by tributyrin. The results showed that tributyrin could significantly alleviate the liver and kidney injury induced by heat stress in dairy cows. Moreover, tributyrin could also significantly reduce the numbers of intermediate cells and increase the level of hemoglobin. Tributyrin could also improve the performance of dairy cows. These results suggested that tributylglycerol may have a positive effect on breast health of dairy cows. In conclusion, these results indicated that tributyrin could relieve HS and increase the production performance of dairy cows by reducing the inflammatory responses of lymphocytes.