Alzheimer’s disease (AD) is the most common neurodegenerative disease that results in memory impairment. Aegle marmelos (L.) Correa (AM) is used as a traditional medicine. AM leaves have the potential to inhibit acetylcholinesterase activity. This study used scopolamine to induce AD in rats. The aim of this study was to investigate the effects of AM leaf extract using this model. Motor and memory functions were tested by the motor activity and Morris water maze (MWM) tests, respectively. The density of the synaptophysin and dendritic spines in the CA1 were detected by immunofluorescence and Golgi impregnation, respectively. The hippocampal histology was reviewed by H&E staining. After the treatment, the latency times in the MWM tests of the AD groups reduced, while the motor activities showed no difference. The density of the synaptophysin of the AD groups increased after the treatments, and that of the dendritic spines also increased in all AD groups post-treatment. The hippocampal tissue also recovered. AM leaf extract can improve cognitive impairment in AD models by maintaining the presynaptic vesicle proteins and dendritic spines in a dose-dependent manner.