Background: Transcranial direct current stimulation (tDCS) is a non-invasive technique that has demonstrated potential in modulating cortical neuron excitability. The objective of this paper is to investigate the effects of tDCS on characteristic parameters of brain functional networks and muscle synergy, as well as to explore its potential for enhancing motor performance. Methods: By applying different durations of tDCS on the motor cortex of the brain, the 32-lead electroencephalogram (EEG) of the cerebral cortex and 4-lead electromyography (EMG) signals of the right forearm were collected for 4 typical hand movements which are commonly used in rehabilitation training, including right-hand finger flexion, finger extension, wrist flexion, and wrist extension. Results: The study showed that tDCS can enhance the brain’s electrical activity in the beta band of the C3 node of the cerebral cortex during hand movements. Furthermore, the structure of muscle synergy remains unaltered; however, the associated muscle activity is amplified (p 0.05). Conclusions: Based on the study results, it can be inferred that tDCS enhances the control strength between the motor area of the cerebral cortex and the muscles during hand movements.