As the global population ages, brain aging has become an increasingly prominent issue. Brain aging involves a decrease in the number of neurons, weakening of synaptic connections, and functional changes in brain regions, resulting in symptoms such as memory decline and cognitive impairment. This review comprehensively examines the research progress on how exercise can delay brain aging by improving brain plasticity. Exercise exerts positive effects on brain aging by influencing synaptic plasticity-related proteins and neurotransmitters, regulating the expression of brain-derived neurotrophic factor (BDNF), reversing neuronal loss, and improving mitochondrial function. However, future research needs to focus on the effects of different types and intensities of exercise on brain aging, as well as the synergistic effects of exercise with other interventions. This review may contribute to the understanding of the mechanisms by which exercise delays brain aging and is crucial for the development of effective prevention and intervention strategies.