Tartary buckwheat (Fagopyrum tataricum), a functional grain known for its medicinal and nutritional properties, has garnered significant attention due to its high flavonoid content and unique health benefits. Heat stress during the flowering stage can lead to sterility in Tartary buckwheat, resulting in reduced yields. This study investigates the effects of a treatment (30/27 °C for 7 days) on flower development, fertility, stress physiology, and gene expression in Tartary buckwheat, while also validating the efficacy of hormone treatments in alleviating the negative effects of heat stress. The results show that fertilization in Tartary buckwheat typically occurs within 3-5 days post-anthesis. By the 5th day, the stamen length in the heat-treated group was reduced by 13.89% compared to the control, while pistil length increased by 35.44%. Heat stress delayed the pistil stigma's transition into its highly receptive phase and caused a significant reduction in pollen viability by 15.25% after 5 days of treatment. Furthermore, after 7 days of treatment, the levels of H