Ras-related C3 botulinum toxin substrate 1 (Rac1) is an important member of the Rho GTPase family. In physiological and pathological cases, Rac1 is closely associated with neuronal plasticity, apoptosis, reactive oxygen species (ROS) production, and inflammatory response. An increasing body of research indicates that Rac1 plays a significant role in diseases of the central nervous system (CNS). This article reviews the physiological role of Rac1 in regulating synaptic morphology and neuronal structural plasticity of neurons, as well as the pathological role of Rac1 in regulating CNS diseases, aiming to provide new insights for the early diagnosis and treatment of CNS diseases.