ObjectiveTo observe the effects of Tongmai Kaiqiao pills on AMP-activated protein kinase （AMPK）/peroxisome proliferator-activated receptor gamma coactivator-1α （PGC-1α） signaling pathway and mitochondrial biogenesis in hippocampal tissue of rats with vascular cognitive impairment （VCI） and to investigate the potential mechanism of Tongmai Kaiqiao pills in improving cognitive impairment in rats with VCI. MethodsTwelve of 72 male SD rats were selected as the sham operation group， and the remaining rats were modelled using the modified 2VO method. The rats that were successfully modelled were divided into the model group， the high-dose group of Tongmai Kaiqiao pills （27.6 g·kg^-1）， the low-dose group of Tongmai Kaiqiao pills （13.8 g·kg^-1）， the combination group （27.6 g·kg^-1 Tongmai Kaiqiao pills + 25 mg·kg^-1 dorsomorphin）， and the donepezil hydrochloride group （0.45 g·kg^-1） according to the random number table method. After four weeks of continuous intraperitoneal injection of the corresponding drugs， the Morris water maze test was used to test the learning and memory ability of rats. Hematoxylin-eosin （HE） staining and Nissl staining were used to detect pathological changes in the hippocampus of the rats. The content of mitochondrial adenosine triphosphate （ATP） in the brain hippocampus was detected by colorimetry， and reactive oxygen species （ROS） level was detected in rat mitochondria by MitoSOX Red assay. Mitochondrial DNA copy number was detected by real-time fluorescent quantitative PCR （Real-time PCR）. Pathological changes in mitochondria were observed by transmission electron microscopy （TEM）， and AMPK， PGC-1α， phosphorylated AMP-activated protein kinase （p-AMPK）， nuclear respiratory factor 1 （Nrf1）， and mitochondrial transcription factor A （TFAM） protein expression in the hippocampus of the rats were detected by Western blot. ResultsCompared with those in the sham operation group， rats in the model group had a reduced number of platform crossings （P<0.01）， significantly prolonged evasion latency （P<0.01）， disorganized neuronal arrangement in the hippocampal region， widened gaps， and blurred nucleus membrane and nucleolus boundaries. The emergence of necrotic cells was visible. The color of the nissl bodies was light， and the number was reduced with severe loss. Mitochondria were atrophied， and cristae were lost. Severe damage was observed. The content of ROS was increased， and the level of ATP was decreased. mtDNA copy number decreased significantly （P<0.01）， and the protein expression of p-AMPK， PGC-1α， Nrf1， and TFAM decreased （P<0.05， P<0.01）. Compared with those in the model group， rats in the high-dose group of Tongmai Kaiqiao pills and donepezil hydrochloride group showed a shorter time to find the platform （P<0.01）， increased number of platform crossings （P<0.01）， restored mitochondrial morphology and structure of the hippocampal neurons， alleviated neuronal death， increased number of nissl bodies， weaken degree of injury， lower content of ROS， and significantly increased levels of ATP and number of copies of mtDNA （P<0.05， P<0.01）. In addition， there was increased protein expression of p-AMPK， PGC-1α， Nrf1， and TFAM （P<0.05， P<0.01）. Compared with the model group， the evasion latency was shortened in the low-dose group of Tongmai Kaiqiao pills （P<0.01）， and the number of platform crossings was increased， but the difference was not statistically significant. The mitochondria were swollen and deformed， and the cristae became shorter and partially disappeared. The degree of damage did not improve significantly， and the number of nissl bodies was increased but not statistically significant. The ROS content decreased （P<0.01）， but there was no significant difference in ATP level and mtDNA copy number. The protein expression of PGC-1α was increased （P<0.05）， but there was no significant difference in the protein expression of p-AMPK， Nrf1， and TFAM， and the results were not statistically significant. Compared with the donepezil hydrochloride group， there was no significant change in the results of each assay in the high-dose group of Tongmai Kaiqiao pills， and the difference was not statistically significant. Compared with the high-dose group of Tongmai Kaiqiao pills， rats in the combination group had a significantly lower number of platform crossings （P<0.01）， a significantly longer evasion latency （P<0.01）， a reduced number of neuronal cells， disorganized tissue structure， swollen and blurred cell outlines， a significant reduction in the number of nissl bodies. Moreover， there was an increase in the content of ROS， a decrease in the level of ATP and the number of mtDNA copies （P<0.01）， and a decrease in the expression of p-AMPK， PGC-1α， Nrf1， and TFAM （P<0.05）. ConclusionTongmai Kaiqiao pills is able to improve cognitive function in rats by activating the AMPK/PGC-1α signaling pathway， promoting mitochondrial biogenesis， and attenuating pathological damage to neurons in the hippocampal region， thereby demonstrating its therapeutic potential.