Beta (15~30 Hz) and Mu (8~14 Hz) rhythm in the human motor cortex have similar activity patterns associated with human actions, and have been viewed as two sub-components of one EEG mechanism for movement representation, planning, understanding, and execution. However, growing evidence suggests that Beta rhythm generated by motor cortex may be independent of Mu rhythm from the same regions. Thus, Beta synchrony might play a different functional role in human action. This review focuses on studies of the functional role of Beta rhythm, and emphasizes evidence that Beta modulation is independent of Mu modulation in is association with human action processing. Current theoretical hypotheses on the function of Beta modulation are discussed based on research on developmental population to help distinguishing ongoing arguments. Finally, future investigations of this topic are proposed.