Objective To observe the morphological changes of cardiomyocytic mitochondria and the reactive oxygen species content in bupivacaine-exposed myocardial cells under electrical stimulation, and to establish an ideal myocardial cell model of bupivacaine poisoning. Methods A Langendorff device was used to separate the cardiomyocytes of male SD rats. The cells were divided into four groups randomly: a DMEM static group, DMEM electric stimulation group, bupivacaine static group and bupivacaine plus electric stimulation group. The experiment was repeated for five times.The cardiomyocytic mitochondrial morphology was observed by transmission electron microscopy, and the ROS content was measured with a multifunctional microplate detector. Results The degree of mitochondrial swelling and the ROS content in the DMEM electric stimulation group were not significantly different from those of the DMEM group ( P > 0. 05), but the mitochondrial swelling in the bupivacaine plus electric stimulation group was significantly higher than that of the bupivacaine group ( P =0. 000), and the ROS output was also significantly increased ( P < 0. 05). Conclusions Under electrical stimulation, cardiomyocytes show rhythmic contractions, allowing better simulation of the myocardial mitochondrial injury during clinical bupivacaine poisoning.