Abstract: Objectives:To observe effects of practicing 24-style Tai Chi Chuan (TCC) on EEG oscillations and mood in middle-aged women. Methods:24 middle-aged women were recruited to participate in the study. Electroencephalography (EEG) oscillations, heart rate, and mood were evaluated by EEG equipment, heart rate telemetry, and psychological questionnaire before and after practicing 24-style TCC. Results: the data indicated that when the heart rate returned to the rest state, compared to the pre-practice, the α relative power significantly increased (P<0.01) and θ relative power remarkably decreased(P<0.05) in the frontal region, while the θ relative power in the central and occipital region significantly declined (P<0.05). After 24-style TCC training, the score of positive mood significantly increased and negative mood was inhibited. In addition, the increase of α relative power in frontal (r=0.830 , P<0.01) and central (r= 0.708 , P<0.01)region sand decrease of θ relative power in frontal(r =-0.675,P<0.01) or central (r=-0.733, P<0.001)regions were closely associated with the positive mood. Conclusion: the data underpin that practicing Tai Chi Chuan could produce mind-physical relaxation in practicers